ARTICLE pubs.acs.org/EF
Cracking Performance and Feed Characterization Study of Catalytic Pyrolysis for Light Olefin Production Xianghai Meng, Chunming Xu, Li Li, and Jinsen Gao* State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, People’s Republic of China ABSTRACT: The catalytic pyrolysis of heavy oils, gas oils, cracked diesel and gasoline fractions was investigated in a confined fluidized-bed reactor. The feed with a high H/C atomic ratio and low aromaticity showed good cracking performance, high feed conversion, and high yield and selectivity of total light olefins (i.e., ethene, propene, and butene). The cracked diesel and gasoline fractions with a low H/C atomic ratio and high aromaticity showed poor secondary cracking performance. A characterization parameter (KCP) was proposed to characterize the cracking performance of various feedstocks. The yield of total light olefins increased with an increase in KCP, despite the catalytic or thermal pyrolysis. KCP could be used as a criterion to evaluate the cracking performance of a feed for the production of light olefins. The cracking performance of a feed was considered desirable for KCP above 3.6 and undesirable for KCP below 2.8. Besides KCP, the United States Bureau of Mineral Correlation Index (BMCI) was also suitable to characterize the cracking performance of various feed for catalytic pyrolysis.
1. INTRODUCTION Light olefins, including ethene, propene, and butene, are considered the backbone of the petrochemical industry. The most prevalent technology for the production of light olefins is steam cracking (SC),1 which is performed in the presence of steam at high temperatures and short residence times. Fluid catalytic cracking (FCC) operates at moderate temperature in the presence of a catalyst and aims to convert low-value feedstocks to high-value gasoline and diesel fractions. This process has been recently used to partly produce light olefins using ZSM5 or modified ZSM-5 zeolite containing catalysts,2 recycling FCC naphtha to the main or secondary riser,3,4 and operating under more severe conditions. Catalytic pyrolysis has been recognized as a promising alternative route for the production of light olefins and has attracted great interest. This process shows several advantages compared to conventional SC, such as higher yields of light olefins, lower energy consumption, and wider feed scope. For the catalytic pyrolysis of naphtha, the yields of ethene and propene are about 10 and 5% higher than those of thermal pyrolysis in the same conditions.5,6 Another research also reports that the ethene-pluspropene yield of catalytic pyrolysis of naphtha at 650 °C is about 10% higher than that of the conventional SC operated at around 820 °C.7 The energy consumption of catalytic pyrolysis, at a scale of 3000 tons of naphtha/day, is about 20% lower than that of the conventional SC process.7 Catalytic pyrolysis processes various feedstocks, such as butanes8,9 or heavier alkanes,10,11 butenes12,13 or heavier olefins,1416 natural gasoline (i.e., pentane, hexane, and heptane extracted from natural gas),17 naphtha,5,6 FCC naphtha,18,19 coker naphtha,19 gas oil,20 heavy oil,21,22 waste tire,23 plastic mixture,24 and bio-oil.25 Low feed cost is another advantage of catalytic pyrolysis when gas oil and heavy oil are used as feed. The cracking rate and performance depend upon the reaction conditions, catalyst, and feed properties. For the catalytic pyrolysis of gas oil and heavy oil, the yield of total light olefins (i.e., r 2011 American Chemical Society
ethene, propene, and butene) shows a maximum when the reaction extent increases.20,21 The reason is that light olefins, especially butene and propene, are intermediate products and can undergo further secondary reactions.26 In comparison to butanes, butenes are easier to react and obtain higher yields of propene and ethene.27 Industrial cracking feeds usually contain paraffins, naphthenes, and aromatics. Generally, the feed with a high content of paraffins shows good cracking performance and high yield of light olefins. However, current studies give more attention to catalyst design, optimization of reaction conditions, and reaction kinetics. Quantitatively evaluating the cracking performance of various feedstocks on catalysts is still difficult. An effective parameter is required for feed selection and optimization, despite the catalyst properties and reaction conditions. In this research, the cracking performance of heavy oils, gas oils, cracked diesels, and gasoline is studied to analyze the effect of feed properties on the yields of light olefins. A parameter is then proposed for feed selection and optimization.
2. EXPERIMENTAL SECTION 2.1. Feedstocks and Catalysts. A total of 13 feeds were used in this research, namely, Chinese Daqing atmospheric residue (Daqing AR), Daqing vacuum residue (Daqing VR), Daqing vacuum gas oil (Daqing VGO), Chinese Huabei atmospheric residue (Huabei AR), heavy gas oil (HGO), light gas oil (LGO), heavy atmospheric gas oil (HAGO), heavy vacuum gas oil (HVGO) derived from Canadian oil sands bitumen, hydrotreated HVGO (HHVGO), and diesel and gasoline fractions from catalytic pyrolysis of HGO and LGO (HGO diesel, LGO diesel, HGO gasoline, and LGO gasoline). The main properties of these feedstocks are listed in Table 1. A zeolite catalyst for catalytic pyrolysis of naphthenic hydrocarbons (CPNH) developed by the China University of Petroleum28 and a Received: January 3, 2011 Revised: March 8, 2011 Published: March 08, 2011 1357
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Table 1. Feed Properties Daqing Daqing Huabei feed
AR
Daqing
HGO
LGO
HGO
LGO
LGO HAGO HHVGO HVGO diesel
diesel
gasoline
gasoline
VR
AR
VGO
HGO
density at 20 °C (g/cm3) 0.9069
0.9221
0.9162
0.8506
0.9294 0.8742 0.8624
0.9136
0.9586 0.9604 0.9302
0.8712
0.8596
molecular weight
577
895
608
426
308
230
260
278
340
205
206
98
101
H content (wt %)
13.16
12.78
12.87
13.58
11.90
12.76
13.07
12.00
11.24
9.58
10.37
9.63
9.87
C content (%)
86.58
86.93
86.51
86.36
87.65
87.21
86.07
87.79
85.22
90.25
89.57
90.32
90.07
H/C atomic ratio
1.82
1.76
1.79
1.89
1.63
1.76
1.82
1.64
1.58
1.27
1.39
1.28
1.31
aromaticity (%) volume average boiling
10.90 542a
13.76 634a
13.00 559a
6.84 435
24.72 400
10.94 283
14.69 306
22.11 362
29.03 415
56.98 275
39.14 270
67.10 96
65.05 93
531a
628a
549a
425
387
270
285
343
405
266
261
83
80
(g/mol)
point (°C) mean average boiling point (°C)
a
BMCI
34.35
35.45
37.51
16.85
57.54
46.75
37.71
54.42
69.72
88.63
75.22
89.67
85.28
K
12.42
12.68
12.38
12.62
11.34
11.29
11.55
11.28
11.10
10.27
10.56
9.85
9.95
PFP
16.73
12.82
13.73
27.59
6.59
16.05
12.40
7.42
5.45
2.24
3.55
1.91
2.02
KH KCP
9.17 3.80
8.26 3.78
8.82 3.70
10.50 4.06
8.63 3.11
10.26 3.46
10.63 3.68
8.96 3.15
8.03 2.96
6.87 2.26
7.73 2.54
8.33 2.32
8.65 2.43
These data were obtained by simulated distillation.
Table 2. Catalyst Properties catalyst
CPNH
CPP
microactivity index
72
70
surface area (m2/g) pore volume (cm3/g)
130 0.21
80 0.19
packing density (g/cm3)
0.88
0.97
020 μm
4.8
1.2
2040 μm
17.2
13.4
4080 μm
47.8
55.9
>80 μm
30.2
29.5
particle size distribution (wt %)
commercial catalytic pyrolysis process (CPP) catalyst developed by the SINOPEC Research Institute of Petroleum Processing29,30 were used in the tests. The main properties of these catalysts are listed in Table 2. Quartz sand (74150 μm) was used as the inert carrier in the experiments. Its surface area and pore volume were 4 m2/g and 0.003 cm3/g, respectively. 2.2. Apparatus and Experimental Conditions. The experiments were conducted in a confined fluidized-bed reactor with a filter on the bed top to prevent catalysts from escaping. The diagram of the apparatus is shown in Figure 1. The apparatus consists of five sections, namely, oil and steam input mechanisms, a reaction zone, a temperature control system, and a product separation and collection system. Experiments were conducted in batches. In each experiment, 50 g of the catalyst or inert carrier was loaded into the reactor, with an effective volume of about 580 cm3. Distilled water was pumped into a furnace to generate steam, which was used to fluidize the catalyst or inert carrier. The feedstock was pumped and mixed with the steam. The mixture was heated to approximately 500 °C in a preheater and then entered the reactor. Reactions took place as the feed made contact with the fluidized catalyst or inert carrier. After the reaction, the oil gas was cooled and separated into liquid and gas samples by the product separation and collection system. After the reaction, the catalyst or inert carrier was drawn out of the reactor by a vacuum pump. The pyrolysis experiments were carried out at temperatures of 620, 660, and 700 °C, with residence times and weight ratios of catalyst/oil and steam/oil being kept constant at around 3 s, 17, and 0.8, respectively.
Figure 1. Diagram of the experimental setup: 1, constant temperature box; 2, steam furnace; 3, feedstock; 4, electronic balance; 5, oil pump; 6, water tank; 7, water pump; 8, preheater; 9, reactor furnace; 10, thermocouple; 11, reactor; 12, inlet and outlet of catalysts; 13, filter; 14, condenser; 15, collecting bottle for liquid products; 16, gas collection vessel; 17, beaker; and 18, gas sample bag.
2.3. Analytical Methods. The gas sample was analyzed by an Agilent refinery gas analyzer (conform to ASTM D1945, D1946, and UOP 539 standard methods) to determine the volume percentage of the components. Data were converted to mass percentages with the state equation of ideal gases. The liquid sample was analyzed with simulated distillation gas chromatography [AC (Analytical Controls, Inc.) SIMDIS HT 750] to obtain the weight percentage of gasoline (C5200 °C), diesel (200350 °C), and heavy oil (>350 °C). The coke content of the spent catalyst or inert carrier was measured with a coke analyzer.
3. RESULTS AND DISCUSSION In this research, the conversion of Daqing AR, Daqing VR, Daqing VGO, Huabei AR, HGO, LGO, HAGO, HVGO, and HHVGO is defined as the sum of the yields of dry gas, liquefied petroleum gas (LPG), gasoline, and coke. The conversion of HGO diesel and LGO diesel is defined as the sum of the yields of dry gas, LPG, gasoline, heavy oil, and coke. The conversion of 1358
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Table 3. Feed Conversion, Yields of Light Olefins, and Selectivity of Total Light Olefins on the CPNH Catalyst at 620 °C (wt %) feed
conversion
yield of ethene
yield of propene
yield of butene
yield of total light olefins
selectivity of total light olefins
Daqing AR
93.03
10.78
23.53
13.23
47.54
51.10
Daqing VR
93.82
9.82
21.92
13.51
45.25
48.23
Huabei AR
93.04
9.44
21.27
13.62
44.32
47.64
Daqing VGO
93.48
9.74
24.15
15.65
49.53
52.98
HGO
67.17
7.58
14.30
7.68
29.56
44.01
LGO
65.68
9.38
16.96
8.42
34.75
52.92
HAGO
69.62
10.25
20.54
8.61
39.41
56.60
HHVGO HVGO
66.15 68.74
7.27 7.90
16.44 14.27
7.99 5.49
31.69 27.65
47.91 40.23
HGO diesel
34.28
1.94
3.16
1.35
6.45
18.82
LGO diesel
42.33
3.72
4.74
1.37
9.83
23.21
HGO gasoline
21.41
2.41
2.10
0.53
5.05
23.58
LGO gasoline
22.74
2.51
2.47
0.66
5.63
24.77
Table 4. Feed Conversion, Yields of Light Olefins, and Selectivity of Total Light Olefins on the CPNH Catalyst at 660 °C (wt %) feed
conversion
yield of ethene
yield of propene
yield of butene
yield of total light olefins
selectivity of total light olefins
Daqing AR
93.87
14.49
24.29
12.70
51.47
54.84
Daqing VR
94.73
13.02
21.87
10.57
45.47
48.00
Huabei AR
95.61
13.10
21.21
12.60
46.91
49.06
Daqing VGO
95.32
14.41
24.54
14.11
53.06
55.66
HGO
76.88
11.25
15.55
6.97
33.77
43.93
LGO HAGO
80.18 81.99
13.19 13.88
18.58 22.02
8.81 11.11
40.58 47.02
50.61 57.34
HHVGO
74.95
11.75
16.57
7.77
36.10
48.16
HVGO
79.26
10.78
15.36
5.83
31.98
40.34
HGO diesel
40.59
3.34
4.10
1.56
9.01
22.19
LGO diesel
54.14
5.18
6.58
2.59
14.35
26.50
HGO gasoline
24.23
2.68
2.02
0.45
5.15
21.24
LGO gasoline
24.94
2.97
2.94
0.79
6.70
26.88
Table 5. Feed Conversion, Yields of Light Olefins, and Selectivity of Total Light Olefins on the CPNH Catalyst at 700 °C (wt %) feed
conversion
yield of ethene
yield of propene
yield of butene
yield of total light olefins
selectivity of total light olefins
Daqing AR
93.60
19.67
21.09
8.38
49.14
52.50
Daqing VR
94.42
18.05
18.60
7.28
43.92
46.52
Huabei AR
94.30
19.29
19.11
6.85
45.26
48.00
Daqing VGO
94.07
20.22
21.37
8.19
49.78
52.92
HGO LGO
81.07 85.75
14.22 16.92
12.73 16.56
3.91 6.46
30.87 39.94
38.08 46.58
HAGO
88.16
18.62
20.23
8.31
47.16
53.49
HHVGO
81.91
13.76
15.86
6.83
36.46
44.51
HVGO
81.58
11.70
12.85
4.74
29.30
35.91
HGO diesel
50.71
4.46
3.84
1.28
9.58
18.89
LGO diesel
58.83
6.52
7.09
2.64
16.26
27.63
HGO gasoline
28.35
3.64
2.37
0.52
6.52
23.01
LGO gasoline
30.26
4.31
2.80
0.61
7.72
25.53
HGO gasoline and LGO gasoline is defined as the sum of the yields of dry gas, LPG, diesel, heavy oil, and coke. 3.1. Cracking Performance of Various Feedstocks. The cracking performance of various feedstocks on the CPNH catalyst at 620, 660, and 700 °C was investigated. Tables 35
show the feed conversion and yields of light olefins at 620, 660, and 700 °C, respectively. The paraffinic feeds, Daqing AR, Daqing VR, Daqing VGO, and Huabei AR, showed good cracking performance. The feed conversion was above 93 wt %; the yield of total light olefins was 1359
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Figure 2. Yield of total light olefins on the CPNH catalyst as a function of K.
above 43 wt %; and the selectivity of total light olefins was about 50%. Among these four feeds, Daqing VGO has the highest H/C atomic ratio and the lowest aromaticity. The yield of total light olefins at 660 °C reached 53 wt %. HGO, LGO, HAGO, HVGO, and HHVGO are naphthenic feeds and showed medium cracking performance. The feed conversion was below 90 wt % at 700 °C and below 70 wt % at 620 °C. The yield of total light olefins, except for HAGO, ranged from 31 to 41 wt %. Among these five feeds, HAGO has the highest H/C atomic ratio and the lowest aromaticity. The yield of total light olefins at 660 and 700 °C reached 47 wt %, and the selectivity of total light olefins was above 50%. In contrast, HVGO has the lowest H/C atomic ratio and the highest aromaticity. The yield of total light olefins was below 32 wt %, and the selectivity of total light olefins was below 41%. HGO diesel, LGO diesel, HGO gasoline, and LGO gasoline are cracked products and have the characteristics of low H/C atomic ratio, high density, and high aromaticity. The cracking performance of these feedstocks was poor. The conversion of diesel fractions was below 60 wt %, and the conversion of gasoline fractions was below 31 wt %. The yield of total light olefins of diesel fractions was below 17 wt %, and the yield of total light olefins of gasoline fractions was below 8 wt %. The selectivity of total light olefins ranged from 18 to 28 wt %, indicating that only about one-fifth to one-fourth of the reaction products was the aimed product. Among all of the cracking feeds, the yield of propene was higher than that of ethene at 620 and 660 °C, and it was close to that of ethene at 700 °C. The yield of ethene at 700 °C was higher than that at 620 and 660 °C; the yield of propene at 660 °C was higher than that at 620 and 700 °C; and the yield of butene at 620 °C was higher than that at 660 and 700 °C. The yield of total light olefins increased with an increase in the reaction temperature for diesel and gasoline feeds, whereas it became a maximum at 660 °C for other feeds. The selectivity of total light olefins became a minimum at 620 °C for diesel and gasoline feeds, whereas it became a minimum at 700 °C for other feeds. The feed with a high H/C atomic ratio showed good cracking performance, high feed conversion, and high yield and selectivity of total light olefins. For the production of light olefins, the good cracking feeds were Daqing VGO, Daqing AR, Daqing VR, Huabei AR, and HAGO.
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Figure 3. Yield of total light olefins on the CPNH catalyst as a function of BMCI.
3.2. Characterization Study of Cracking Feeds. 3.2.1. Reported Feed Characterization Parameters. The cracking perfor-
mance depends upon feed property, catalyst property, and operating conditions. Several parameters are used to characterize the cracking performance of various feeds. The universal oil products (UOP) K factor, shown in eq 1, is used to characterize the cracking performance of straight-run or hydrocracked gas oils.31 The United States Bureau of Mineral Correlation Index (BMCI), shown in eq 2, is used to characterize the cracking performance of light hydrocarbons or gas oils, especially for ethene production by steam cracking.31 In eqs 1 and 2, T is the average boiling point (K), with the mean average boiling point often used, TV is the volume average boiling point (K), and d is the relative density. Catalytic pyrolysis is a new process, and it is worth studying whether K and BMCI are suitable or not to characterize the cracking performance of various feeds for catalytic pyrolysis. T 1=3 15:6 d15:6
ð1Þ
48640 15:6 þ 473:7d15:6 456:8 TV
ð2Þ
K ¼ 1:216
BMCI ¼
Figures 2 and 3 illustrate the yield of total light olefins on the CPNH catalyst at 620, 660, and 700 °C as a function of K and BMCI, respectively. The feed with a large K value or small BMCI value showed good cracking performance. The yield of total light olefins increased with an increase in K and a decrease in BMCI. The cracking performance of a feed was good if its K value was above 12 or its BMCI value was below 45. It is proven that both K and BMCI could be used to characterize the cracking performance of various feedstocks for catalytic pyrolysis. The average boiling point is required to calculate the values of both K and BMCI, but it was not easy to obtain for heavy oils by usual methods in the past. A characterization parameter (KH), shown in eq 3, is reported to characterize the processing performance of heavy oils.32,33 In eq 3, H/C is the H/C atomic ratio, M is the mean molecular weight (g/mol), and F20 is the density at 20 °C (g/cm3). Figure 4 shows the yield of total light olefins on the CPNH catalyst at 620, 660, and 700 °C as a function of KH. The result showed that KH could not effectively characterize the cracking performance of the investigated feeds. For example, the KH value of Daqing AR, Daqing VR, and Huabei 1360
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Figure 4. Yield of total light olefins on the CPNH catalyst as a function of KH.
Figure 6. Yield of total light olefins on the CPNH catalyst as a function of KCP.
Figure 5. Yield of total light olefins on the CPNH catalyst as a function of PFP.
Figure 7. Yield of ethene on the CPNH catalyst as a function of KCP.
AR was lower than that of HAGO and LGO, but the yield of total light olefins of these three residua was higher than that of HAGO and LGO. KH ¼ 10
H=C M 0:1236 F20
ð3Þ
The authors reported a feed parameter (PFP), shown in eq 4, to characterize the cracking performance of various feeds.34 In eq 4, H/C is the H/C atomic ratio, and fa is the aromaticity of the feed. Figure 5 shows the yield of total light olefins on the CPNH catalyst at 620, 660, and 700 °C as a function of PFP. As the PFP value increased, the yield of total light olefins first increased and then varied slightly when the PFP value was above 20. The result showed that PFP could characterize the cracking performance of the investigated feeds. However, valuable instruments, such as a nuclear magnetic resonance spectrometer or mass spectrometer, are required to determine the aromaticity of heavy feeds. PFP ¼
H=C fa
ð4Þ
to characterize the cracking performance of various feeds for the production of light olefins. The meaning of H/C, M and F20 was the same as that in eq 3. The H/C atomic ratio is a chemical property that shows the hydrogen saturation of the average molecule of the feed. The experiment showed that the feed with a large H/C atomic ratio obtained a high yield of light olefins. The molecular weight (M) denotes the average molecule size, and a large M value favors the production of light olefins. Density indicates both the molecule size and the molecule type. The feed with a large molecule size and aromatic structure has high density. KCP ¼ ðH=CÞa M b F20 c
ð5Þ
For the catalytic pyrolysis of various feeds on the CPNH catalyst, the yield of total light olefins increased with an increase in KCP. We assumed that the yield of total light olefins increased linearly with the value of KCP. The value of the power exponents (i.e., a, b, and c) in eq 5 was calculated by the least-squares regression analysis of the experimental data on the CPNH catalyst at 660 °C, resulting in eq 6. KCP ¼
3.2.2. New Feed Characterization Parameter. This research proposed a new characterization parameter (KCP), shown in eq 5, 1361
ðH=CÞM 0:1 F20
ð6Þ
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Figure 8. Yield of propene on the CPNH catalyst as a function of KCP.
Figure 9. Yield of total light olefins on the CPP catalyst as a function of KCP.
Figures 68 illustrate the yields of total light olefins, ethene, and propene, respectively, on the CPNH catalyst at 620, 660, and 700 °C as a function of KCP. The yields of total light olefins, ethene, and propene increased with an increase in KCP; the regularity was good. The results showed that KCP could characterize the cracking performance of the investigated feeds. From the viewpoint of the yield of total light olefins, the cracking performance at 660 °C was close to that at 700 °C and was better than that at 620 °C. KCP could be used as a criterion to evaluate the cracking performance of a feed. KCP above 3.6 was considered desirable because the yield of total light olefins exceeded 45 wt %. When the yield of total light olefins was lower than 30 wt %, the value of KCP was below 2.8. The catalyst property is an important factor influencing the yields of light olefins. The cracking performance on the CPP catalyst was investigated to test the applicability of KCP. Figure 9 shows the yield of total light olefins on the CPP catalyst at 620, 660, and 700 °C as a function of KCP. The yield of total light olefins increased with an increase in KCP; the regularity was also good. From the viewpoint of the yield of total light olefins, the cracking performance at 660 °C was close to that at 700 °C and was better than that at 620 °C, which is similar to the cracking performance on the CPNH catalyst. Reactions of catalytic pyrolysis involve catalytic cracking and thermal cracking.21 This paper investigated the thermal cracking
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Figure 10. Yield of total light olefins on quartz sand as a function of KCP.
performance on quartz grain to test the applicability of KCP further. The yield of total light olefins increased with an increase in KCP; the regularity was also good (Figure 10). From the viewpoint of the yield of total light olefins, the cracking performance at 700 °C was the best and that at 620 °C was the worst, which is different from the cracking performance on the CPNH or CPP catalyst. 3.2.3. Comparison of Feed Characterization Parameters. Parameters K, BMCI, KH, PFP, and KCP are empirical and have their own suitable application scope. These parameters with the exception of KH could characterize the cracking performance of various feeds for catalytic pyrolysis. The yield of total light olefins increased with an increasing value of K, PFP, and KCP and decreased with an increasing value of BMCI. However, the yield of total light olefins varied slightly with the K value below 10.2 and above 12 and with the PFP value above 16 (Figures 2 and 5). This shows that the cracking performance was similar despite the value of parameters within the above ranges, which did not favor in the comparison of the cracking performance of various feeds. The yield of total light olefins increased almost linearly with an increasing value of KCP and decreased almost linearly with an increasing value of BMCI. This favored in the comparison of the cracking performance of various feeds. Therefore, KCP and BMCI were better than K and PFP for the characterization of the cracking performance of various feed for catalytic pyrolysis.
4. CONCLUSIONS (1) Gas oils and residua with a high H/C atomic ratio showed good cracking performance. Cracked diesel and gasoline fractions with a low H/C atomic ratio showed poor secondary cracking performance. (2) A characterization parameter (KCP) was proposed to characterize the cracking performance of various feeds. KCP could effectively characterize the cracking performance of the investigated feeds. The yield of total light olefins increased with an increase in KCP on catalysts or an inert carrier. (3) KCP could be used as an evaluation criterion for the cracking performance of a feed. The cracking performance of a feed was good if the KCP value was above 3.6 and poor if the KCP value was below 2.8. (4) The cracking performance of feedstocks became better with larger values of K, PFP, and KCP and smaller values of 1362
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’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ ACKNOWLEDGMENT Financial support was provided by the National Science Fund for Distinguished Young Scholars of China (Grants 20525621 and 20725620) and the Major Research Plan of the Ministry of Education of China (Grant 307008). ’ REFERENCES (1) Picciotti, M. Novel ethylene technologies developing, but steam cracking remains king. Oil Gas J. 1997, 95 (25), 53–58. (2) Fraczek, K. Fluid catalytic cracking and propylene production growth. Przem. Chem. 2003, 82 (2), 78–83. (3) Verstraete, J.; Coupard, V.; Thomazeau, C.; Etienne, P. Study of direct and indirect naphtha recycling to a resid FCC unit for maximum propylene production. Catal. Today 2005, 106 (14), 62–71. (4) Li, C. Y.; Yang, C. H.; Shan, H. H. Maximizing propylene yield by two-stage riser catalytic cracking of heavy oil. Ind. Eng. Chem. Res. 2007, 46 (14), 4914–4920. (5) Jeong, S. M.; Chae, J. H.; Lee, W. H. Study on the catalytic pyrolysis of naphtha over a KVO3/R-Al2O3 catalyst for production of light olefins. Ind. Eng. Chem. Res. 2001, 40 (26), 6081–6086. (6) Jeong, S. M.; Chae, J. H.; Kang, J. H.; Lee, S. H.; Lee, W. H. Catalytic pyrolysis of naphtha on the KVO3-based catalyst. Catal. Today 2002, 74 (34), 257–264. (7) Yoshimura, Y.; Kijima, N.; Hayakawa, T.; Murata, K.; Suzuki, K.; Mizukami, F.; Matano, K.; Konishi, T.; Oikawa, T.; Saito, M.; Shiojima, T.; Shiozawa, K.; Wakui, K.; Sawada, G.; Sato, K.; Matsuo, S.; Yamaoka, N. Catalytic cracking of naphtha to light olefins. Catal. Surv. Jpn. 2000, 4 (2), 157–167. (8) Lu, J. Y.; Zhao, Z.; Xu, C. M.; Zhang, P.; Duan, A. J. FeHZSM-5 molecular sieves—Highly active catalysts for catalytic cracking of isobutane to produce ethylene and propylene. Catal. Commun. 2006, 7 (4), 199–203. (9) Jiang, G. Y.; Zhang, L.; Zhao, Z.; Zhou, X. Y.; Duan, A. J.; Xu, C. M.; Gao, J. S. Highly effective P-modified HZSM-5 catalyst for the cracking of C-4 alkanes to produce light olefins. Appl. Catal., A 2008, 340 (2), 176–182. (10) Pant, K. K.; Kunzru, D. Catalytic pyrolysis of n-heptane on unpromoted and potassium promoted calcium aluminates. Chem. Eng. J. 2002, 87 (2), 219–225. (11) Jung, J. S.; Park, J. W.; Seo, G. Catalytic cracking of n-octane over alkali-treated MFI zeolites. Appl. Catal., A 2005, 288 (12), 149–157. (12) Xue, N. H.; Nie, L.; Fang, D. M.; Guo, X. F.; Shen, J. Y.; Ding, W. P.; Chen, Y. Synergistic effects of tungsten and phosphorus on catalytic cracking of butene to propene over HZSM-5. Appl. Catal., A 2009, 352 (12), 87–94. (13) Zhu, X. X.; Liu, S. L.; Song, Y. Q.; Xie, S. J.; Xu, L. Y. Catalytic cracking of 1-butene to propene and ethene on MCM-22 zeolite. Appl. Catal., A 2005, 290 (12), 191–199. (14) Nawaz, Z.; Tang, X.; Wei, F. Hexene catalytic cracking over 30% sapo-34 catalyst for propylene maximization: Influence of reaction conditions and reaction pathway exploration. Braz. J. Chem. Eng. 2009, 26 (4), 705–712. (15) Nawaz, Z.; Tang, X.; Zhu, J.; Wei, F.; Naveed, S. Catalytic cracking of 1-hexene to propylene using SAPO-34 catalysts with different bulk topologies. Chin. J. Catal. 2009, 30 (10), 1049–1057.
ARTICLE
(16) Le Van Mao, R.; Muntasar, A.; Yan, H. T.; Zhao, Q. Catalytic cracking of heavy olefins into propylene, ethylene and other light olefins. Catal. Lett. 2009, 130 (12), 86–92. (17) Souza, M. J. B.; Fernandes, F. A. N.; Pedrosa, A. M. G.; Araujo, A. S. Selective cracking of natural gasoline over HZSM-5 zeolite. Fuel Process. Technol. 2008, 89 (9), 819–827. (18) Wang, G.; Xu, C. M.; Gao, J. S. Study of cracking FCC naphtha in a secondary riser of the FCC unit for maximum propylene production. Fuel Process. Technol. 2008, 89 (9), 864–873. (19) Liu, W. K.; Meng, X. H.; Zhao, X.; Wang, G.; Gao, J. S.; Xu, C. M. Pyrolysis performances of catalytic cracking naphtha and coker naphtha on inert carriers and an active catalyst. Energy Fuels 2009, 23 (12), 5760–5764. (20) Li, L.; Wang, G.; Meng, X. H.; Xu, C. M.; Gao, J. S. Catalytic pyrolysis of gas oil derived from Canadian oil sands bitumen. Ind. Eng. Chem. Res. 2008, 47 (3), 710–716. (21) Meng, X. H.; Xu, C. M.; Gao, J. S.; Li, L. Studies on catalytic pyrolysis of heavy oils: Reaction behaviors and mechanistic pathways. Appl. Catal., A 2005, 294 (2), 168–176. (22) Meng, X. H.; Xu, C. M.; Gao, J. S.; Li, L.; Liu, Z. C. Catalytic and thermal pyrolysis of atmospheric residue. Energy Fuels 2009, 23 (1), 65–69. (23) Dung, N. A.; Klaewkla, R.; Wongkasemjit, S.; Jitkarnka, S. Light olefins and light oil production from catalytic pyrolysis of waste tire. J. Anal. Appl. Pyrolysis 2009, 86 (2), 281–286. (24) Serrano, D. P.; Aguado, J.; Escola, J. M.; Rodriguez, J. M.; Morselli, L.; Orsi, R. Thermal and catalytic cracking of a LDPEEVA copolymer mixture. J. Anal. Appl. Pyrolysis 2003, 689, 481–494. (25) Gayubo, A. G.; Valle, B.; Aguayo, A. T.; Olazar, M.; Bilbao, J. Olefin production by catalytic transformation of crude bio-oil in a twostep process. Ind. Eng. Chem. Res. 2010, 49 (1), 123–131. (26) Meng, X. H.; Xu, C. M.; Gao, J. S. Secondary cracking of C4 hydrocarbons from heavy oil catalytic pyrolysis. Can. J. Chem. Eng. 2006, 84 (3), 322–327. (27) Li, L.; Gao, J. S.; Xu, C. M.; Meng, X. H. Reaction behaviors and mechanisms of catalytic pyrolysis of C4 hydrocarbons. Chem. Eng. J. 2006, 116 (3), 155–161. (28) Shen, B. J.; Gao, J. S.; Xu, C. M.; Zhao, L.; Li, X. F.; Wu, P. Catalyst composition for treating heavy feedstocks. U.S. Patent Applicaton 20070209969, Sept 13, 2007. (29) Shi, Z. C.; Zhang, F. M.; Liu, S. H. Catalyst for catalytic pyrolysis process for the production of light olefins and the preparation thereof. U.S. Patent 6,211,104, April 3, 2001. (30) Guan, J. J.; Wang, X. Q.; Yu, Z. Q.; Chen, Z. Y.; Liu, Q. L.; Liao, Y. Pillared clay catalysts for heavy oil catalytic pyrolysis process and the preparation method thereof. U.S. Patent 6,342,153, Jan 29, 2002. (31) Xu, C. M.; Yang, C. H. Petroleum Refining Engineering, 4th ed.; China Petroleum Industry Press: Beijing, China, 2009; pp 6365. (32) Yang, G. H.; Wang, R. A. The supercritical fluid extractive fractionation and the characterization of heavy oils and petroleum residua. J. Pet. Sci. Eng. 1999, 22 (13), 47–52. (33) Shi, T. P.; Xu, Z. M.; Cheng, M.; Hu, Y. X.; Wang, R. A. Characterization index for vacuum residua and their subfractions. Energy Fuels 1999, 13 (4), 871–876. (34) Meng, X. H.; Xu, C. M.; Gao, J. S.; Liu, Z. C. Influence of feed properties and reaction conditions on catalytic pyrolysis of gas oils and heavy oils. Fuel 2008, 87 (12), 2463–2468.
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