Catalytic Cracking of Light Crude Oil to Light Olefins and Naphtha over

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Catalysis and Kinetics

Catalytic Cracking of Light Crude Oil to Light Olefins and Naphtha over ECat and MFI: MAT versus ACE and Effect of High Reaction Temperature Sulaiman Saleh Fahad Al-Khattaf, Mian Rahat Saeed, Abdullah Aitani, and Michael T Klein Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b00691 • Publication Date (Web): 13 Apr 2018 Downloaded from http://pubs.acs.org on April 17, 2018

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Catalytic Cracking of Light Crude Oil to Light Olefins and Naphtha over ECat and MFI: MAT versus ACE and Effect of High Reaction Temperature Sulaiman Al-Khattafa,b*, Mian Rahat Saeeda, Abdullah Aitania and Michael T. Kleina,c a

Center for Refining & Petrochemicals, The Research Institute, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia b

Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia c

Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA

E-mail addresses of authors: 

Sulaiman S. Al-Khattaf: [email protected]



Mian Rahat Saeed: [email protected]



Abdullah M. Aitani: [email protected]



Michael T. Klein: [email protected]

* Corresponding author: Sulaiman S. Al-Khattaf, Postal Address: Center for Refining & Petrochemicals, P.O. Box 5040, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia, Email address: [email protected]; Phone: +966-13-860-2029, Fax: +966-13-860-4509

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ABSTRACT The catalytic cracking of light paraffinic crude oil with an API gravity of 51° was compared using two laboratory testing techniques, a fixed-bed microactivity test (MAT) unit and a fixed fluidized-bed Advanced Cracking Evaluation (ACE) unit. Both units were operated using equilibrated FCC catalyst (E-Cat), MFI zeolite (ZSM-5) and E-Cat/MFI (equal mixture with MFI) at two temperatures (550 and 600 °C) and constant catalyst-to-oil ratio of 4.0. Despite the different hydrodynamics in MAT and ACE reactors, both units gave similar catalyst ranking based on the conversion of 221+ C feed fraction at 550 and 600 C in the order of: E-Cat > E-Cat/MFI > MFI, which is attributed to diffusion limitation of MFI catalyst. While both testing techniques showed variation in product yield structure (dry gas, LPG, naphtha and unconverted 221+ C) over the three catalysts, the ACE unit gave significantly higher coke yield compared with MAT. The highest yield of light olefins was obtained over ECat/MFI (29 wt%) at 600 C in MAT compared with MFI (23 wt%) and E-Cat (21 wt%). The effect of high temperature (650 C) on crude oil cracking in ACE showed an increase in conversion and light olefins yield for all catalysts as well as in thermal cracking case (no catalyst) associated with a decrease in naphtha yield. The highest yields of light olefins (35 wt%) was obtained at a naphtha yield of 37 wt% over E-Cat/MFI compared with 30 wt% and 41 wt%, respectively, for no catalyst. However, the operation at high temperature introduced the adverse effects of thermal cracking resulting in high yields of dry gas (14 wt% for E-Cat and 17 wt% for no-catalyst) which reflects a significant contribution of pyrolytic cracking reactions.

Keywords: Crude oil, catalytic cracking, light olefins, naphtha, MAT, ACE, high temperature

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1. INTRODUCTION Amid the declining demand for the transportation fuels (mainly gasoline), refiners are focusing on upgrading and integrating their operations with high-value petrochemicals production. In 2016, petrochemical feedstocks accounted for 12.7 % of global crude oil demand or 12 million barrels per day (b/d) and this demand is forecast to reach 18 million b/d in 2030. 1 Light olefins (ethylene and propylene) and naphtha-based aromatics are the largestvolume basic chemicals with a global production capacity of 240 and 85 million tons, respectively, in 2016.2 Light olefins are mainly used in the production of polyolefins, styrene, ethylene oxide, ethylene dichloride, alpha olefins, propylene oxide, acrylonitrile, cumene, acrylic acid and oxo alcohols. Between 2016 and 2030, the global demand for transportation fuels is forecast to increase at an average annual rate of 1.6% compared with a 3.5% growth rate for light olefins and aromatics. As shown in Table 1, the global production capacities of light olefins (ethylene and propylene) and aromatics are expected to reach 385 and 133 million tons, respectively, by the year 2030.2 While ethylene is produced by the steam cracking (SC) of hydrocarbons (mainly naphtha, ethane and liquefied petroleum gas-LPG), propylene is co-produced by naphtha SC, fluid catalytic cracking (FCC) of vacuum gas oil (VGO) and on-purpose propylene technologies such as propane dehydrogenation (PDH), metathesis, and methanol-to-propylene (MTP). During the last three decades, the FCC process has seen modifications in hardware, catalysts, recycling of FCC naphtha and operation at high severity to enhance the yields of propylene and other light olefins in addition to its conventional production of gasoline.3,4 In many FCC units worldwide, MFI zeolite is added to the USY catalyst to increase propylene yield by selectively cracking naphtha range olefins.5,6 Propylene yield increased from 3-6 wt% in conventional FCC to more than 20 wt% in several new high-olefins processes. The flexibility of the FCC unit in handling a variety of paraffinic feedstocks has allowed some refiners to crack new feeds such as shale oil and light conventional crude oils.7 Several oil and chemical companies have investigated the direct conversion of crude oil to light olefins and naphtha in order to bypass some of the costly refining processes. In 2014, ExxonMobil was the first to commercialize a flexible ethylene steam cracker that uses light crude oil as a feedstock.8 Other companies have announced plans to build oil-to-chemicals complexes in China, Indonesia, Saudi Arabia and others. The direct conversion of crude oil helps in reducing raw material costs, energy consumption and carbon emissions. The direct 2 ACS Paragon Plus Environment

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conversion of crude oil to chemicals is an emerging feedstock trend for petrochemicals aimed at meeting the growing industrial demand for light olefins and aromatics. This route is economically attractive in regions where steam naphtha cracking is predominant or where ethane and LPG are becoming scarce feedstocks. Corma et al. reviewed various strategies and modeling for the direct cracking of light crude oil and its fractions to produce chemicals.9,10 In the thermal cracking of Arab Extra Light (AXL) crude oil, it was found that heavy fraction cracks faster than middle distillates and naphtha fractions with similar selectivity to light olefins in the temperature range of 560-640 C.10 Our recent work on the cracking of various types of light crude oils in microactivity test (MAT) unit11,12 and riser simulator13 showed that various types of crude oils can be cracked over FCC catalysts blended with MFI and the cracked liquid products can be recycled to enhance the production of light olefins and naphtha.12 Various laboratory testing techniques such as MAT, Advanced Cracking Evaluation (ACE), CREC Riser Simulator reactor, micro-downer, and Davidson Circulating Riser (DCR) pilot plant have been developed to assess the crackability of various hydrocarbon feedstocks and to determine the activity of FCC catalysts.14-15 The advantages of the fixed-bed MAT and the fixed fluidized-bed ACE testing are that they require small amounts of material (feed and catalyst) and they have excellent reproducibility. While MAT testing is widely used to evaluate the performance of FCC catalysts, the ACE unit has gained more acceptance due to better mass and heat transfer characteristics.14 It is therefore important to understand the differences, if any, in conversion, selectivities and product yields between these two reactors. In this work, we have compared the results of direct catalytic cracking of Arab Super Light (ASL) crude oil in MAT and ACE units at 550 C over three catalysts comprising an equilibrium FCC catalyst (E-Cat), steamed commercial MFI catalyst and an equal mixture of E-Cat and MFI (E-Cat/MFI). The effects of high-temperature catalytic and thermal cracking of ASL crude oil on the yield of light olefins and naphtha were investigated in ACE between 550 and 650 C over the three catalysts at constant catalyst-to-oil ratio (CTO) of 4.0. 2. EXPERIMENTAL SECTION 2.1. Crude Oil Feed and Catalysts. The Arab Super Light (ASL) crude oil used in this work was procured from a local refinery. ASL is a light crude oil discovered in the mid-1980s and extracted from fields in Central Saudi Arabia. It has an API gravity of 51°, low sulfur 3 ACS Paragon Plus Environment

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content of 0.11 wt% and negligible metal (Ni, V) content.11 The USY E-Cat and MFI additive were obtained from a local refinery. The E-Cat was calcined at 500 °C for 3 h at a rate of 5 °C/min before use. Similar to the fresh FCC catalyst, the MFI was hydrothermally treated in 100 % steam at 810 °C for 6.0 h before MAT and ACE tests. These conditions are based on a steaming procedure developed by our laboratory to equilibrate the MFI activity to what is expected under FCC industrial conditions.11-13 In a typical commercial FCC additive, MFI crystals are mixed with an amorphous matrix (such as alumina or silica-alumina) to have physical strength and attrition resistance similar to FCC catalyst. Current commercial MFI additives are available with crystal MFI content ranging from 25 to 60 wt%. The E-Cat/MFI was prepared by physical mixing of 50 wt% E-Cat and 50 wt% MFI additive. The MFI additive content in E-Cat/MFI blended catalyst was based on weight percent of whole MFI additive and not the MFI crystal content of the additive. 2.2. Catalyst Characterization. The SiO2 and Al2O3 contents in E-Cat were determined using an inductively coupled plasma spectrometer (ULTIMA 2, ICP-OES) from Horiba Scientific. The textural properties of the catalysts were measured by N2 adsorption at 77 K utilizing a Micromeritics ASAP-2020 analyzer. The samples (50 mg) were outgassed at 240 C for 2 h under N2 flow prior to measurements. The surface area was determined from the desorption data within 0.06-0.2 relative pressure (P/Po). The acidity of the catalysts was analyzed using temperature programmed desorption (TPD) of NH3 using BEL-CAT-A-200 chemisorption instrument. The calcined sample (0.1 g) was pretreated for 1 h at 500 °C using He (50 ml/min). After cooling down to 100 °C, it was exposed to He/NH3 mixture (volume ratio of 95/5 vol%) for 30 min. Gaseous ammonia was removed by purging He for 1 hr at 100°C and then TPD was performed using He at a rate of 10 °C/min up to 600 °C and the desorbed NH3 was monitored using TCD detector. More details on the characterization methods are presented elsewhere.11-13 2.3. Cracking Tests. The cracking of ASL crude oil tests was conducted in a micro-activity test (MAT) unit with a fixed-bed reactor and an Advanced Cracking Evaluation (ACE) with fluidized fixed-bed reactor. Mass balances were calculated for all tests and only those greater than 96% or lower than 102% were accepted. 2.3.1 Cracking in MAT. The MAT unit was manufactured by Sakuragi Rikagaku, Japan, in accordance to ASTM D-3907. The MAT feed injector was modified to handle ASL feed instead of conventional VGO. Gaseous products were collected in a water displacement and 4 ACS Paragon Plus Environment

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liquid products were collected in a chilled-glass receiver. All MAT tests were conducted at two temperatures (550 and 600 °C) and constant catalyst-to-oil (CTO) ratio of 4.0 g/g. The weight of the catalyst was 4.0 g and that of the ASL feed was 1.0 g. The feed injection time or time-on-stream (TOS) was 30 s and the catalyst was stripped at 550 C using nitrogen gas at 30 cc/min for 9 min based on results from our previous work.11,12 A Horiba Carbon Analyzer (EMIA 220V) was used to determine the coke deposited on the spent catalyst by combustion method. 2.3.2 Cracking in ACE. The ACE-R+ unit was manufactured by Kayser Technology Inc., USA.16 The unit contains an automated fixed-fluidized bed reactor in accordance to ASTM D-7964. More details of the ACE unit and its schematic representation can be found in previous publication.17 Because of the low density of the ASL feed (API > 50°), it was difficult to generate product selectivity curves in ACE by changing CTO, instead, the three catalysts were compared at constant CTO of 4.0 g/g. The amount of catalyst was 6.0 g while the amount of ASL feed was 1.5 g and the feed injection rate was 1.18 g/min resulting in a feed injection time (TOS) of 76 s. ACE tests were conducted at atmospheric pressure and the effect of reaction temperature was investigated at four temperature levels (550, 600, 625, and 650 °C). After the reaction, the remaining hydrocarbons were stripped from the catalyst bed and the reactor by continuing N2 purge for a period of 9 min. A few tests were conducted with no-catalyst (empty reactor) in the ACE reactor to investigate the thermal cracking behavior of the ASL feed. The effect of temperature in the range of 550 to 650 was investigated at similar conditions to catalytic cracking except that the catalyst hopper was left empty. During the experiment, only feed was injected for 76 s at feed rate of 1.2g/min. The feed line in ACE goes all the way close to the bottom of reactor (2.9 cm above the bottom) at the cracking temperature (the part of feed line in the reactor is about 37 cm). There was enough time and heat available for feed evaporation and there was no need for using an inert material (deactivated material) as heat carrier. During the cracking and stripping modes, the liquid product was collected in a glass receiver, which was located at the end of the reactor exit and was maintained at a temperature of -15 °C. The gaseous products were collected in a gas receiver by water displacement method. After the completion of stripping process, the catalyst was regenerated in the presence of air at 700 C to measure the amount coke deposited on the catalyst. A catalytic converter was


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used to convert CO to CO2 at 535 C. The coke deposited on the catalyst was burned off with air in regeneration mode and the total CO2 was analyzed using online IR spectroscopy. 2.3.3 Analysis of Cracked Products. For both MAT and ACE tests, the dry gas (H2 and C1C2) and LPG (C3-C4) in the gaseous products were analyzed using a Micro-Gas Chromatograph (GC) Agilent 3000A utilizing multi-column, multi-channel system and four thermal conductivity detectors (TCD). The boiling point distribution of the liquid products was determined using a standard simulated distillation (SimDis) according to ASTM D-2887 using Shimadzu GC 2010 Plus with a flame ionization detector (FID). Three liquid fractions were defined as: naphtha (C5-221 °C), light cycle oil-LCO (221–343 °C) and heavy cycle oilHCO (343+ °C). The results of gas and liquid analyses were used to calculate conversion and product yields for ASL. Since the ASL feed contains an appreciable amount of naphtha (41wt.%), the conversion is defined as the percent of 221C+ fractions in ASL (middle distillates and heavy oil) cracked to gaseous and naphtha fractions as given below:11,12 Conversion (221+ C), wt.% =

Weight % of (221 ℃+) in ASL Feed − Weight % of (221 ℃+) in Product ∗ Weight % of (221 ℃+) in ASL Feed

100%

A similar definition was used for the conversion of sub-fractions in the 221-343 C and 343+ C lumps. 3. RESULTS AND DISCUSSION 3.1. Feed and Catalyst Characterization. The physical and distillation properties of ASL crude oil are presented in Table 2. The simulated distillation results showed that ASL contains 41.2 wt % naphtha, 31.0 wt% middle distillates (221-343 C) and 27.8 wt% heavy oil (343+ C) fractions which boil in the LCO and HCO boiling ranges. ASL crude oil has a higher ratio of 343-C/343+C hydrocarbons at 2.6 compared with conventional crude oils such as Arabian Light crude oil which has a ratio of 1.11 The feed has a K-Factor (UOP Characterization factor) of 12.55 indicating the paraffinic nature of the feed. Naphtha composition (paraffins, olefins, naphthenes, and aromatics) of ASL feed was determined using a Shimadzu GC with BP-1 PONA capillary column and FID detector. The PIONA analysis of the naphtha fraction showed a high paraffinic content of 34 wt% n-paraffins, 32 wt% iso-paraffins, 19 wt% naphthenes and 15 wt% aromatics.


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The chemical and physical properties of E-Cat and MFI catalysts are presented in Table 3. The Si/Al molar ratios of E-Cat and MFI obtained by ICP analysis were 3.3 and 5.6 respectively. As mentioned in Section 2.1, MFI is a commercial additive which is not pure ZSM-5 zeolite. It contains amorphous matrix material such as alumina or silica-alumina. The results of nitrogen adsorption evaluation showed that N2 adsorption isotherm was a type I isotherm for the two catalysts which is typical of zeolitic materials. The BET surface area and micropore volume calculated from the nitrogen sorption isotherms are also shown in Table 3. The micropore volume was determined using the t-plot method. The NH3-TPD profiles of E-Cat and MFI additive showed two major desorption peaks (Figure 1). These two peaks have maxima in low temperature (100-300 C) and high temperature (300-550 C) regions which correspond to weak and strong acid sites of the catalysts, respectively.18 The total acidity for E-Cat was 0.09 mmol/g and that for MFI was 0.49 mmol/g. The amount of weakly bounded ammonia desorbed in lower temperature was higher for MFI as compared to E-Cat. The lower desorption peaks were assigned to ammonia molecules adsorbed either on NH4+ species formed on Brønsted acid sites or on Na+ cations. During TPD measurement, the adsorption of ammonia was carried out at 100 °C followed by an inert gas purging for about 1 h at the same temperature to remove physisorbed ammonia. More details on catalyst characterization results can be seen in our previous publications.11-13 3.2. Catalytic Cracking: MAT versus ACE. The catalytic cracking of ASL crude oil was conducted using two FCC laboratory testing techniques: a fixed-bed MAT unit and a fixed fluidized-bed ACE unit at two temperatures (550 and 600 C) and constant CTO ratio of 4.0. The results are compared and discussed in terms of conversion and product yields, namely dry gas, LPG, light olefins, naphtha, LCO, HCO and coke. Taking into consideration the differences in the cracking environment between MAT and ACE units, contact and feed injection time, the performance of the three catalysts (E-Cat, E-Cat/MFI and MFI) were compared at constant CTO of 4.0. Similar to the catalytic cracking of VGO, the desired products in ASL cracking (light olefins and naphtha) are considered intermediate products and undesired products (dry gas without ethylene and coke) are considered end-products.15 3.2.1 Conversion in MAT and ACE. The results of ASL conversion and product yields in both MAT and ACE over the three catalysts at 550 and 650 C are presented in Tables 4 and 5. As mentioned earlier, the conversion is defined as the percentage of 221+ C fractions that


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are cracked to lighter products such as naphtha, LPG (C3-C4) and dry gas (H2, C1-C2). The naphtha fraction in the ASL feed was 41 wt% and the 221+ C fractions boiling within LCO and HCO range were 31 wt% and 28 wt%, respectively. In FCC operation, the feed composition and catalyst properties have direct effect on conversion level and product yield structure.19-21 The results of conversion showed similar ranking of catalysts in MAT and ACE for the three catalysts at both temperatures and constant CTO. At 550 C, the catalyst ranking in ACE unit in terms of conversion was as follows: E-Cat (66 wt%) > E-Cat/MFI (64 wt%) > MFI (38 wt%) and at 600 C the conversion decreased in similar order: E-Cat (72 wt%) > ECat/MFI (69 wt%) > MFI (57 wt%). At 550 C, the conversion of feed fraction boiling within 221-343 C (similar to LCO fraction) was 46 wt% over E-Cat and E-Cat/MFI in both MAT and ACE units. The same trend was observed at 600 C with conversion over the two catalysts increasing to 56 wt%. However, the LCO-range boiling fraction showed higher conversion over MFI in MAT (35 wt%) compared with ACE (25 wt%) at 550 C and similar conversion (39 wt%) in both units at 600 C (Tables 4 and 5). On the other hand, the conversion of feed fraction boiling above 343 C (similar to HCO fraction) was 80 wt% over E-Cat and E-Cat/MFI at 550 C in MAT and ACE units and increased to 90 wt% upon increasing the temperature to 600 C in both units. In the case of MFI, the ACE unit showed higher conversion (52 wt%) for HCO boiling fraction compared with 36 wt% in MAT at 550C. The same trend was observed at 600 C with ACE conversion of HCO reaching 80 wt% compared with a MAT conversion of 68 wt%. These results are in agreement with other reported results.19-21 3.2.2 Product yields in MAT and ACE. The product yields of ASL cracking over the three catalysts in MAT and ACE are presented in Tables 4-5 and Figure 2. Several yield ratios of selected products are used to compare the performance of the three catalysts at 550 and 650 C. These yield ratios are: dry gas/isobutane, known as cracking mechanism ratio (CMR), propylene/ethylene ratio (P/E) and butanes/butenes ratio known as hydrogen transfer coefficient (HTC).22-26 These ratios are presented in Tables 4-5. In MAT and ACE, the average yields of dry gas (hydrogen, methane, ethane and ethylene) over E-Cat/MFI and MFI were similar at 550 C (about 3.7 wt%) and 600 C (about 8.3 wt%) compared with 1.8 wt% and 5.3 wt% over E-Cat, respectively. The highest yield of coke (2.0 wt%) was obtained over E-Cat at 600 C in ACE.20 At 550 C, MAT and ACE showed 8 ACS Paragon Plus Environment

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similar results over E-Cat and E-Cat/MFI which produced the highest LPG yield (27.6 wt%). The main products in LPG yield over E-Cat/MFI were propylene (9.2 wt%), butenes (6.9 wt%), and isobutane (4.4 wt%). At 600 C, the LPG yield over E-Cat/MFI increased to 34 wt% in MAT associated with an increase in propylene yield, reaching 14.2 wt%. The increase in propylene yield over E-Cat/MFI compared with E-Cat was at the expense of decreasing naphtha yield. On the other hand, MFI produced the lowest LPG yield (16.6 wt%) in ACE at 550 C due to low propylene yield (5.9 wt%) and very low isobutane yield (1.3 wt%). At 550 C, the highest yields of C2-C4 light olefins (19.4 wt%) and propylene (9.4 wt%) were obtained over E-Cat/MFI in ACE compared with 15 wt% and 7 wt % over

E-Cat,

respectively. However, at 600 C, the highest yield of light olefins (29 wt%) were obtained in MAT over E-Cat/MFI compared with 23 wt% over MFI and 21 wt% over E-Cat. The highest ethylene (6 wt%) and propylene yields (14 wt%) were also obtained over E-Cat/MFI catalyst. Our previous studies in MAT showed that the highest yield of light olefins was obtained over E-Cat blended with 25 wt% MFI zeolite in the cracking of AXL crude oil.11,12 The ratios for HTC, CMR and P/E in MAT showed similar results to ACE unit for the three catalysts at 550 and 600 C, as presented in Tables 4-5. Compared with MFI, the total acidity of the large pore E-Cat was the lowest (Table 3) and its HTC at 550 C was the highest at 1.5 (Table 4) allowing bimolecular hydrogen transfer reactions to occur, which meant lower yield of light olefins over E-Cat.22,27 Upon increasing the temperature to 600 C, the HTC of the three catalysts decreased with increasing temperature corresponding to a decrease in C4 paraffins and an increase in of C4 olefins. On the other hand, the highest CMR (6.7) was obtained over MFI at 600 C due to its high yield of dry gas (> 8 wt%) and low yield of isobutane (< 2 wt%) in both MAT and ACE units. The net naphtha yield over the three catalysts showed similar ranking in MAT and ACE at 550 and 600 C as follows: E-Cat > E-Cat/MFI > MFI. The E-Cat results showed similar naphtha yields (53 wt%) in MAT and ACE compared with naphtha content of 41 wt% in ASL feed. The naphtha yields over the other two catalysts were lower than E-Cat, however, the yields in ACE were higher by 4-8 wt% compared with MAT. As discussed earlier, the average yields of LCO over E-Cat and E-Cat/MFI were similar in MAT and ACE at 550 C (17 wt%) and 600 C (13 wt%) compared with yields over MFI at 22 wt% and 19 wt%, respectively. The yields of HCO were also similar over E-Cat/MFI in MAT and ACE at 550 C (5 wt%) and 600 C (3 wt%) compared with yields over MFI at 18 wt% and 9 wt% in 9 ACS Paragon Plus Environment

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MAT, respectively. However, the yields over MFI in ACE were lower by 30% compared with MAT at both temperatures. 3.2.3 Comparison of MAT and ACE Results. Despite the differences in the hydrodynamics between the catalyst beds in MAT and ACE units, the conversion results over E-Cat and ECat/MFI in both units suggest that there is no advantage of either technique in the cracking of ASL light crude oil at 550 and 600 C. There was a minimal dilution effect of MFI blending with E-Cat on conversion. The low conversion over MFI catalyst in both MAT and ACE units is attributed to the diffusion limitation of this medium pore zeolite in the cracking of 221+ C fraction despite the higher acidity of MFI additive (Table 3). However, ACE showed better performance in the cracking of the 343+ C fraction over MFI compared with MAT which is attributed to better hydrodynamics of ACE.19-21 The differences in heat and mass transfer characteristics between the MAT and ACE units resulted in a clear variation in product structure for the three catalysts, especially the yields over MFI. All catalysts showed higher coke yield in ACE compared with MAT due to the difference in contact mode between feed molecules and catalyst particles.21 The higher yield of dry gas over E-Cat/MFI and MFI compared with E-Cat is attributed to their higher yield of ethylene in MFI blended catalysts. The yield of LPG over the three catalysts did not show a clear advantage of any of the testing techniques over the other. While the highest light olefins yield (19.4 wt%) was obtained over E-Cat/MFI in ACE at 550 C, the same catalyst produced the highest yields of light olefins (29 wt%) in MAT at 600 C. The variation in naphtha yield over the three catalysts is attributed to catalyst properties and to the cracking of C 6-C8 naphtha range olefins to light olefins over MFI blended catalysts.22 The ranking of catalysts in terms of HCO yields in both MAT and ACE units is as follows: MFI > E-Cat = E-Cat/MFI. This confirms that MFI has little effect on the cracking of 343+ C fraction due its shape selectivity and medium pore size.20,22 3.3. Effect of High-Temperature Cracking. The effect of reaction temperature on the cracking of ASL crude oil was investigated in ACE between 550 and 650 C over the three catalysts (E-Cat, E-Cat/MFI and MFI) and no-catalyst (thermal cracking case). The main objective was to study the impact of high temperature on the conversion and the yields of light olefins, naphtha and other cracked products. The operation at high temperature introduced the adverse effects of thermal cracking resulting in high yields of dry gas which


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reflects a significant contribution of pyrolytic cracking reactions. Several competing reactions that originate from catalytic and thermal cracking take place in the conversion of hydrocarbons.4 Various reactions take place in the cracking of ASL crude oil over zeolite catalysts which comprise protolytic monomolecular and bimolecular reactions in addition to contribution from thermal cracking. Thermal

cracking

reactions

include

bond

fission,

beta-scission,

isomerization,

dehydrogenation, oligomerization, alkylation, cyclization, hydrogen transfer, and others. Thermal cracking proceeds via primary radicals which are formed via bond fission at various C-C bonds, creating free radicals whose beta-scission reactions lead to ethylene. The free radical produced during beta scission can undergo a hydrogen abstraction reaction, creating a stable product and another free radical that can undergo beta scission to ethylene. The repetition of this reaction cycle leads to the formation of high yield of ethylene in addition other products.10,23,24 It has been reported that paraffins cracking over USY E-Cat is a bimolecular reaction mechanism while the cracking over medium-pore MFI only monomolecular reactions take place resulting in smaller size products (dry gas) and lower hydrogen transfer reactions (more light olefins).22,23 The ASL cracking over E-Cat is in agreement with the behavior of VGO cracking under FCC conditions in which the yield of C1-C2 gases is small because their formation should go through primary carbenium ions, which are energetically unstable. 3.3.1 Effect of Temperature on Conversion. The variations in ASL conversion over E-Cat, E-Cat/MFI and MFI between 550 and 650 °C and CTO ratio of 4.0 and the thermal cracking case are presented in Table 6 and Figure 3. The effects of temperature on conversion and product yields showed a steady increase in the yield of total gas (dry gas + LPG) for all the cases reaching a maximum of 48.3 wt% over E-Cat/MFI at 650 C. As reported earlier, the monomolecular mechanism becomes more dominant at higher temperatures with increased formation of dry gas, LPG, and coke.4 The overall conversion (221+ C) increased with increasing temperature for all cases. At 550 C, the conversion of the feed fraction boiling within HCO range (343+ C) was about 84 wt% over E-Cat and E-Cat/MFI compared with a conversion of about 54 wt% over MFI and thermal cracking case. As seen Figure 3, two sets of curves were obtained; one set of higher conversion (> 65 wt%) for E-Cat and E-Cat/MFI and another set of lower conversion (> 37 wt%) for MFI and the thermal cracking case. As the temperature was increased, the conversion gap between the two sets decreased from 30 11 ACS Paragon Plus Environment

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Energy & Fuels

wt% at 550 C to 3 wt% at 650 C. Between 550 and 650 C, the conversion over E-Cat and E-Cat/MFI increased by 20 % (from 66 wt% to 79 wt%), whereas the conversion over MFI and thermal case was doubled (from 36 wt% to 77 wt%). 3.3.2 Dry Gas and Coke Yields. The dry gas yield for all catalysts and thermal cracking case showed a sharp increase with increasing temperature (Figure 4). Within the temperature range of 550-650 C, dry gas yield over E-Cat increased from 1.9 and to 13.7 wt.% associated with an increase in ethylene, methane and ethane yields. The increase in dry gas over E-Cat/MFI and MFI was from about 3.5 to 15.0 and 17.1 wt%, respectively. The highest increase in dry gas was seen for the thermal cracking case reaching 18.9 wt% (8.8 wt% ethylene) at 650 C. The other components of dry gas (C1 and C2) showed also significant increase over all cases. In order to compare the variation in dry gas yield at high temperature, the CMR ratio (dry gas/isobutane) was plotted against temperature as shown in Figure 5. The CMR for E-Cat, ECat/MFI and MFI varied between 0.4 (E-Cat) at 550C and 14.1 (MFI) at 650 C. This reflects a significant contribution of protolytic cracking over MFI compared with the classical carbenium ion chemistry (beta scission cracking) over E-Cat which involves bimolecular processes such as intermolecular hydrogen transfer.23,24 The CMR is a useful parameter to reveal in a qualitative manner the extent to which the two acid-catalyzed cracking mechanisms take place.23 As reported by Wielers et al., CMR decreases with increasing pore dimensions, indicating that with decreasing pore dimensions as with MFI, cracking proceeds more and more via the protolytic route.23 Because of the relatively medium pore size of MFI

and its higher acidity compared with E-Cat, the interaction between the catalytic surface of MFI and the reactants is larger resulting in a higher conversion of linear olefins and a higher production of ethylene than with the E-Cat. The CMR for the thermal cracking case showed a very sharp increase above 600 C reaching 27 at 650 C, which may be attributed to the highly activated free radical chain reaction mechanism for ethylene formation and low yield of isobutane.23,24 The increase in coke yield was the highest over E-Cat reaching 3.1 wt% at 650 C, however, the other cases did not show any significant increase in coke yield (about 2 wt%) upon increasing temperature to 650 C. 3.3.3 LPG Yield. The yield of LPG (C3–C4) yield increased linearly with temperature over all the catalysts and the thermal cracking case as shown in Table 6 and Figure 4. The increase


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in LPG yield is mainly attributed to the increase in the yields of propylene and butenes. The E-Cat and E-Cat/MFI showed the highest yield of LPG with similar increasing trend reaching 33 wt% at 650 C. The gap in LPG yields between E-Cat and MFI narrowed down from 10 wt% at 550 to 3 w% at 650 C. In the thermal cracking case, LPG yield was the lowest at 550 C (8.7 wt%), however, it increased to 24.7 wt% at 650 C, thereby narrowing the gap with E-Cat to about 8 wt %. Figure 6 presents the effect of temperature on the yields of LPG paraffins (mainly butanes) and LPG olefins. The yields of LPG paraffins over E-Cat and ECat/MFI decreased from 11 to 7 wt% at 550 and 650 C, respectively. However, the yield of LPG paraffins over MFI and thermal cracking case were about constant at 5.5 and 3.5 wt%, respectively. The yield of LPG olefins increased for all cases reaching about 25 wt% over the three catalysts and 21.2 wt% for the thermal cracking case. The average ratio of the yield of LPG olefins/LPG paraffins (LPG olefinicity) increased from 0.6 at 550 C to 0.8 at 650 C. 3.3.4 Naphtha Yield. As shown in Table 2, the naphtha fraction in the ASL feed (C5-221C) was about 41.2 wt%, with highly paraffinic composition (66%), followed by naphthenes (19%), and aromatics (15%). In general, the reactivity of FCC naphtha is 1-2 orders of magnitude smaller than that of a normal VGO and the only significantly reactive components are normal and branched C7+ olefins.22 The net naphtha yield for all cases was the highest among cracked products (35-52 wt%), which is attributed to unconverted naphtha in the feed and to the formation of naphtha from the cracking of LCO and HCO fractions.7 The naphtha yield decreased with increasing temperature for all cases. As shown in Figure 4 and Table 6, the highest percentage drop in naphtha yield between 550 and 650 C was seen over E-Cat (27.5 %), followed by E-Cat/MFI (22.1 %), no-catalyst (19.5 %) and MFI (16.9 %). The results show a direct correlation between the decrease in naphtha yield and increase in light olefins yield, which may be attributed to the hydrogen transfer activity (HTC) of MFI compared with other catalysts. At 650 C, the highest naphtha yield (41.2 wt%) was obtained over the thermal cracking case, compared with the other three catalysts. 3.3.5 LCO and HCO Yields. The variation in the LCO and HCO yields as a function of temperature is plotted in Figure 4 and presented in Table 6. As discussed earlier, the conversion of the 221+ C fraction in the feed increased by 20% over E-Cat and E-Cat/MFI, and doubled for MFI, and the thermal cracking case within 550-650 C. Initially, some of the LCO is formed from the cracking of HCO resulting in higher LCO yield.19 However, at 650 C, both LCO and HCO yields decreased over E-Cat and E-Cat/MFI by 40 %, compared with 13 ACS Paragon Plus Environment

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Energy & Fuels

about 70 % drop over MFI and the thermal cracking case. The yields of LCO and HCO over the four cases decreased to about 10 wt% and 2.8 wt%, respectively, at 650 C. These results indicate that about 68 wt% and 90 wt% of the feed fractions boiling within LCO and HCO ranges have been converted at 650 C into lighter fractions, mainly naphtha, LPG and dry gas. 3.3.6 Comparison of Light Olefins Yields. The overall yield of C2–C4 light olefins increased with increasing temperature over all cases as shown in Figure 7. At 650 C, the yields of light olefins were in the following order: E-Cat/MFI > MFI > E-Cat > thermal cracking. The increase in light olefins yields with increasing temperature may be attributed to the conversion of reactive iso-paraffins and olefins species in the naphtha-range fraction.22,28,29 For example, the yield of light olefins over E-Cat/MFI increased by 80% from 19.4wt% at 550 C to 34.9 wt% at 650 C associated with a decrease of 22% in naphtha yield from 47.0 to 36.6 wt%, respectively (Figure 8). The distribution of ethylene and propylene within the yield of light olefins at 650 C varied among the catalysts with propylene showing the highest content (> 45 wt%) over the three catalysts followed by ethylene at 22 wt% compared with 38 wt% and 30 wt% for the thermal cracking case, respectively. The highest yields of LPG olefins (26.5 wt%) and propylene (16.3 wt%) were obtained over E-Cat/MFI at 650 C while the highest ethylene yield was obtained over MFI at 9.0 wt% compared with 6.2 wt% over E-Cat at 650 C. The P/E yield ratio decreased with the increase in temperature due to the strong contribution from thermal cracking resulting in higher yield of ethylene for all cases. 4. CONCLUSIONS The crackability of light crude oil (51 API) was compared in a fixed-bed MAT and fixed fluidized-bed ACE units over three catalysts (E-Cat, MFI, and E-Cat/MFI) at 550 and 600 C and constant CTO of 4.0. Based on conversion, MAT and ACE gave similar catalyst ranking in the order of: E-Cat > E-Cat/MFI > MFI which is attributed to diffusion limitation of MFI catalyst in the cracking of 221+ C feed fraction. Both testing techniques showed variation in product yield structure (dry gas, LPG, naphtha and unconverted 221+ C fraction) over the three catalysts. However, the ACE unit gave significantly higher coke yield compared with MAT. The highest yields of light olefins (29 wt%) and propylene (14 wt%) were obtained


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

over E-Cat/MFI in MAT at 600 C, compared with 21 wt% and 10 wt% over E-Cat, respectively. The effect of reaction temperature on ASL cracking in ACE between 550 and 650 C showed an increase in conversion and light olefins yield for all catalysts as well as in the thermal cracking case (no catalyst). The highest yields of light olefins (35 wt%) and propylene (16 wt%) were obtained over E-Cat/MFI at 650 C. The high yield of dry gas at 650 C (14 wt% for E-Cat and 17 wt% for thermal cracking case) is attributed to the formation of ethylene and methane which reflects a significant contribution of pyrolytic cracking at high temperature. It is concluded that FCC process and catalyst technologies will have an important role in the direct cracking of crude oil for the production of light olefins and high-aromatics naphtha. ACKNOWLEDGEMENTS The authors appreciate the support from the Research Institute at King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, Saudi Arabia. Michael T. Klein acknowledges collaborations with and support of colleagues via the Saudi Aramco Chair Program at KFUPM and Saudi Aramco. The contributions of Mr. Ramzi Al-Shuqaih and Mr. Roy Villarmino in MAT and ACE operation are highly appreciated. REFERENCES (1)

IEA, World Energy Outlook, International Energy Agency (IEA), Nov. 2017, Paris.

(2) Fagg, L Long-term Sustainability in Commodity Petrochemicals: An outlook for olefins and aromatics, Presented at Asia Petrochemical Industry Conference (APIC), May 2017 Sapporo, Japan. (3) Vogt, ET, Weckhuysen, BM. Fluid catalytic cracking: Recent developments in the grand old lady of zeolite catalysis. Chem. Soc. Rev. 2015, 44, 7342–7370. (4) Blay, V, Louis, B, Miravalles, R, Yokoi, T, Peccatiello, KA, Clough, M, Yilmaz, B. Engineering zeolites for catalytic cracking to light olefins. ACS Catal. 2017, 7, 6542-6566. (5) Arandes, J, Abajo, I, Fernández, I, Azkoiti, MJ, Bilbao, J. Effect of HZSM-5 zeolite addition to a fluid catalytic cracking catalyst: study in a laboratory reactor operating under industrial conditions. Ind. Eng. Chem. Res. 2000, 39, 1917-1924. (6) Aitani, A., Yoshikawa, T., Ino, T. Maximization of FCC light olefins by high severity operation and ZSM-5 addition. Catal. Today 2000, 60, 111-117. (7) Bryden K, Federal M, Habib, TE, Schiller R. Processing tight oils in FCC: Issues, opportunities and flexible catalytic solutions. Grace Cat. Tech. Catalagram 2014, 114, 3-22. (8) Amghizar, I., Vandewalle, L., Van Geem, K., Marin, G. New trends in olefin production, Engineering, 2017, 3, 171-178.


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(9) Corma A, Corresa E, Mathieu Y, Sauvanaud L, Al-Bogami, S, Al-Ghrami, M, Bourane A. Crude oil to chemicals: light olefins from crude oil, Catal. Sci. Technol. 2017, 7, 12-46. (10) Corma, A, Sauvanaud, L, Mathieu, Y, Al-Bogami, S, Bourane A, Al-Ghrami, M. Direct crude oil cracking for producing chemicals: Thermal cracking, Fuel 2018, 211, 726736 (11) Usman A, Siddiqui, M, Hussain A, Aitani A, Al-Khattaf S. Catalytic cracking of crude oil to light olefins and naphtha: Experimental and kinetic modelling, Chem. Eng. Res. Des. 2017, 120, 121-137. (12) Usman, A, Aitani, A, Al-Khattaf, S. Catalytic cracking of light crude oil: effect of feed mixing with liquid hydrocarbon fractions, Energy Fuel, 2017, 31, 12677-12684. (13) Al-Khattaf, S, Ali, SA Catalytic cracking of Arab Super Light crude oil to light olefins: An experimental and kinetic study, Energy Fuel, 2018, 32, 2234-2244. (14) Wallenstein, D., Haas, A., Harding, R.H. Latest developments in microactivity testing: Influence of operational parameters on the performance of FCC catalysts, App. Catal. A, 2000, 203, 23-36. (15) Corma, A, Sauvanaud, L. FCC testing at bench scale: New units, new processes, new feeds, Catal. Today 2013, 218-219, 107-114. (16) Kayser, JC. Versatile fluidized bed reactor, U.S. Patent No. 6,069,012, May 30, 2000. (17) Passamonti, F, de la Puente, G, Gilbert, W, Morgado, E, Sedran, U. Comparison between fixed fluidized bed (FFB) and batch fluidized bed reactors in the evaluation of FCC catalysts. Chem. Eng. J. 2012, 183, 433-447. (18) Al-Dughaither, A, de Lasa, H. HZSM-5 zeolites with different SiO2/Al2O3 ratios. Characterization and NH3 desorption kinetics. Ind. Eng. Chem. Res. 2014, 53, 15303−15316. (19) Ng, S, Zhu, Y, Humphries, A, Zheng, L, Ding, F, Gentzis, T, Charland, JP, Yui, S. FCC study of Canadian oil-sands derived vacuum gas oils. 1. Feed and catalyst effects on yield structure. Energy Fuel, 2002, 16, 1196-1208. (20) Ng, S, Zhu, Y, Humphries, A, Nakajima, N, Tsai, TY, Ding, F, Ling, H, Yui, S. Key observations from a comprehensive FCC study on Canadian heavy gas oils from various origins: yield profiles in batch reactors. Fuel Proc. Tech. 2006 87, 475-485. (21) Passamonti, F, de la Puente, G., Sedran, U. Comparison between MAT flow fixed bed and batch fluidized bed reactors in the evaluation of FCC catalysts. 1. Conversion and yields of the main hydrocarbon groups, Energy Fuel, 2009, 23, 1358-1363. (22) Den Hollander, MA, Wissink, M, Makkee, M, Moulijn, JA. Gasoline conversion: Reactivity towards cracking with equilibrated FCC and ZSM-5 catalysts. Appl. Catal. A 2002, 223, 85-102 (23) Wielers, F, Vaarkamp, M, Post, MF. Relation between properties and performance of zeolites in paraffin cracking. J. Catal. 1991, 127, 51-66. (24) Dwyer, J, Rawlence, DJ. (1993). Fluid catalytic cracking: Chemistry. Catal. Today, 1993, 18, 487-507. (25) Siddiqui MAB, Aitani AM, Saeed MR, Al-Yassir N, Al-Khattaf S. Enhancing propylene production from catalytic cracking of Arab Light VGO over novel zeolites as FCC catalyst additives. Fuel 2011, 90, 459-466. 16 ACS Paragon Plus Environment

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(26) Zhang, J, Shan, H, Chen, X, Li, C, Yang, C. In situ upgrading of light fluid catalytic cracking naphtha for minimum loss. Ind. Eng. Chem. Res. 2013, 52, 6366-6376. (27) Mahgoub, KA, Al-Khattaf, S. Catalytic cracking of hydrocarbons in a riser simulator: The effect of catalyst accessibility and acidity. Energy Fuel, 2005, 19, 329-338. (28) Zhao, X, Roberie, TG. ZSM-5 additive in fluid catalytic cracking. 1. Effect of additive level and temperature on light olefins and gasoline olefins. Ind. Eng. Chem. Res. 1999, 38, 3847-3853. (29) Li, X, Li, C, Zhang, J, Yang, C, Shan, H. Effects of temperature and catalyst to oil weight ratio on the catalytic conversion of heavy oil to propylene using ZSM-5 and USY catalysts. J. Nat. Gas Chem. 2007, 16, 92-99.


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Energy & Fuels

List of Figures Figure 1.

NH3-TPD acidity profiles for (a) E-Cat and (b) MFI catalysts.

Figure 2.

Comparison of ASL feed composition with MAT and ACE product yields for at 550 C and 4.0 CTO over E-Cat, E-Cat/MFI, and MFI.

Figure 3.

Effect of reaction temperature on conversion of ASL in ACE over ( ) E-Cat, E-Cat/MFI, () MFI and () No-catalyst.

Figure 4.

Effect of temperature on product yields for ASL cracking in ACE over () E-Cat, () MFI, () E-Cat/MFI and () No-catalyst.

Figure 5.

Effect of temperature on cracking mechanism ratio (CMR = dry gas/isobutane) for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () nocatalyst.

Figure 6.

Effect of temperature on the yields of (a) LPG paraffins and (b) LPG olefins for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () nocatalyst.

Figure 7.

Effect of temperature on the yield of C2-C4 light olefins for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () no-catalyst.

Figure 8.

Effect of reaction temperature on the yield structure of ASL crude oil cracking in ACE over E-Cat/MFI catalyst.


)

Energy & Fuels

Figure 1. NH3-TPD acidity profiles for (a) E-Cat and (b) MFI catalyst.13

100

12

90 80

Distribution, wt%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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41

15

10

11

70

19 12

13

16

19

7

11

11

C1-C4 Paraffins

60

40

52

31

44

Naphtha

47 LCO

30

20

20 10

43

35

54

50

C2-C4 Olefins

28

0

ASL Crude

Oil

16

4

6

5

ACE

MAT

ACE

16

6 MAT

E-Cat

HCO

18

17

23

18

13

MAT

ACE

Coke

E-Cat/MFI

MFI

Figure 2. Comparison of ASL feed composition with MAT and ACE product yields at 550 C and 4.0 CTO over E-Cat, E-Cat/MFI, and MFI.


Page 21 of 28

85 80 75 70

Conversion, %

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

65 60 55 50 45 40 35

30 525

550

575

600

625

650

675

Temperature, ºC

Figure 3. Effect of reaction temperature on conversion for ASL cracking in ACE over () ECat, () E-Cat/MFI, () MFI and () No-catalyst.


Energy & Fuels

10

20

Ethylene

Propylene 8

Yield, wt%

Yield, wt%

15

10

6

4

5

2

0

0 525

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675

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Temperature, ºC

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675

Temperature, ºC

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Naphtha

LPG

45

55 35

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Yield, wt%

40

30 25 20

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15 35 10

30

5 525

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Temperature, ºC

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4

Coke

Dry gas 15

3

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575

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2

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0 525

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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5 0

0 525

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Temperature, ºC

575

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Figure 4. Effect of temperature on product yields for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () no-catalyst. 21 ACS Paragon Plus Environment

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30

CMR ratio

25 20 15 10 5 0 525

550

575

600

625

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675

Temperature, ºC Figure 5. Effect of temperature on the Cracking Mechanism Ratio (CMR = dry gas yield/isobutene yield) for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () no-catalyst.

30

(a) LPG Paraffins

12

(b) LPG Olefins

25

9

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Yield, wt%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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6

20 15 10

3 5

0

0

525

550

575 600 625 Temperature, ºC

650

675

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650

Figure 6. Effect of temperature on the yields of (a) LPG paraffins and (b) LPG olefins for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () no-catalyst.


675

Energy & Fuels

40 C2-C4 Light Olefins

35 30 Yield, wt%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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25 20 15 10 5 0

525

550


650

675

Figure 7. Effect of reaction temperature on the yield of C2-C4 light olefins for ASL cracking in ACE over () E-Cat, () E-Cat/MFI, () MFI and () no-catalyst.

Figure 8. Effect of reaction temperature on the yield structure of ASL crude oil cracking in ACE over E-Cat/MFI catalyst.


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Energy & Fuels

Table 1. Actual and Forecasted Global Production Capacity of Light Olefins and Aromatics.2 Commodity petrochemical Ethylene Propylene Benzene (BZ) Para-xylene (PX)

Production capacity, million ton/year Actual 2016 Forecasted 2030 145 230 95 155 45 63 40 70

Annual growth, % (2016-2030) 3.3 3.4 3.3 4.0

No. of new units (capacity basis, million ton/year) 70 (1.2) 60 (1.0) 35 (0.5) 25 (1.2)

Table 2. Properties of Arab Super Light (ASL) Crude Oil Feed. Property Gravity, API Density at 15C, kg/m3 Sulfur (wt.%) Vanadium (ppm) Nickel (ppm) Microcarbon residue (wt.%) Kin. Viscosity, @ 21 C (cSt) Elemental analysis (wt.%) Carbon Hydrogen Nitrogen Simulated distillation (C) Initial boiling point 50% Final boiling point Distillation cuts (wt.%) Naphtha (C5-221C) Middle distillates (221-343 C) Heavy oil (343C+) PIONA naphtha fraction (wt.%) UOP K-Factora a Calculated according to UOP (2007) Method

Value 51.3 774 0.11 1

Catalytic Cracking of Light Crude Oil to Light Olefins and Naphtha over

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