The Consideration of Different Effective Zeolite Based Catalysts and

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The consideration of different effective zeolite based catalysts and heating rate on the pyrolysis of Styrene Butadiene Rubber (SBR) in a stirred reactor Mehrdad Seifali Abbas-Abadi, and Mehdi Nekoomanesh Haghighi Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b02743 • Publication Date (Web): 10 Oct 2017 Downloaded from http://pubs.acs.org on October 16, 2017

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Energy & Fuels

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The consideration of different effective zeolite based catalysts and heating rate on the pyrolysis of

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Styrene Butadiene Rubber (SBR) in a stirred reactor

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Mehrdad Seifali Abbas-Abadi*, Mehdi Nekoomanesh Haghighi

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Polymerization Engineering, Iran Polymer and Petrochemical Institute (IPPI), P.O. Box 14965/115,

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Tehran, Iran

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* Corresponding author. Tel.: +98 2144787020; fax: +98 2144787021.

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E-mail address: [email protected] (M.S. Abbas-Abadi).

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Abstract

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The pyrolysis products as well as composition of the condensed products generated from Styrene

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Butadiene Rubber (SBR) degradation have been investigated with reference to different zeolite based

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catalysts. The effects of different catalysts containing used FCC, Gallium promoted used FCC (Ga/FCC),

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HZSM-5 and mordenite have been studied on the SBR degradation using a stirred semi-batch reactor.

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Main products obtained were light hydrocarbons within the gasoline range though the Ga/FCC and used

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FCC tended to produce more condensed products with aromatics as the main product. Meanwhile, the

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non-isothermal mass losses of SBR were measured using a thermo-gravimetric analyzer (TGA) at heating

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rates of 5, 15, 30, 45 and 90oC min-1 until the furnace wall temperature reached 600oC. The TGA

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degradation trends of SBR was in between the TGA’s of a usual plastic and Poly Butadiene Rubber

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(PBR). Activation energies decreased by increasing the heating rate (154.7-131.5 kJ mol-1) although

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activation energy of the fast pyrolysis shows a significant decrease in comparison with the others.

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slow pyrolysis, the double bonds in SBR chains could prepare the proper media for crosslink mechanism

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while phenyl groups boost the chain scission and unzipping mechanisms. In other word, the fast pyrolysis

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follows the chain scission and un-zipping mechanisms along the most times of degradation.

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Keywords: SBR; Ga/FCC; catalyst; TGA; GC/MS; crosslink; chain scission.

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In

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Energy & Fuels

1. Introduction

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Tires and used rubbers as present potential problems, due to the large volume produced, the durability and

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the releasable harmful components, are under consideration in many countries. Because they are highly

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flammable, durable and non-biodegradable and consume valued space in landfills and create enormous

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risks [1-3]. Synthetic Styrene-Butadiene Rubber (SBR) is widely used in the rubber industry, especially in

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different vehicles tire treads with attention to suitable mechanical and dynamic properties [4]. The used

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rubbers in scrap tires as high flammable organic materials have high volatile and fixed carbon contents

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with heating value greater than the classic fuels. The better understanding and using of thermal

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degradation processes especially pyrolysis and gasification of various rubber products can play an

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important role from the view of protecting environment against biological damage, fire risk and

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greenhouse emission and it allows to produce the valuable materials and energy [5-7].

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Pyrolysis is a thermal degradation of natural and synthetic polymers at high temperatures in the absence

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of oxygen. At pyrolysis, the polymer chains are degraded and broken up to produce the evaporable low

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molecular weights and or the non-evaporable high molecular weights such as coke. The type, size and

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amount of evaporable and non-evaporable components depend on the process parameters such as polymer

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type, temperature, heating rate, catalyst type and amount, reactor, carrier gas and maybe some other

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unknown parameters [8-11].

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Hirschler [12] has proposed four mechanism containing End-chain scission or unzipping, Random-chain

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scission, Chain-stripping and Cross-linking for the thermal degradation of polymers. It appears that all of

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these mechanisms happen in the pyrolysis process with different shares. The share of each mechanism

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depends strongly on the polymer type though the process parameters such as temperature, heating rate and

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catalyst type and ratio can change the degradation mechanism perfectly [13-15].

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The degradation mechanisms can affect on the product yield, type and size. For example, unzipping

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boosts the monomer production and chain scission leads to linear scission but cross-linking mechanism in

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the complex process tends to produce the non-linear molecules and aromatics and also increases the

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polyaromatics as non-evaporables [14-16]. 3 ACS Paragon Plus Environment

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Catalytic pyrolysis of rubber wastes is one of the most acceptable and feasible processes to control the

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degradation mechanism and development of cracking processes allowing the products to be upgraded by

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conversion into the desirable products. Catalytic pyrolysis of the rubber chains over zeolites occurs at the

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catalyst surface or over the acid sites present in the pore channels. The low molecular weighs compounds

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so formed can subsequently enter the zeolite pores undergoing different secondary reactions, depending

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on the varied specification of the zeolites though the catalyst role decreases with the temperature rising

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[15, 17-22].

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The practical results on the pyrolysis of different rubbers and the related mechanisms are few. The goal of

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this paper is to elucidate the effect of different catalysts and heating rates on the SBR pyrolysis and give

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better understanding of how the effective parameters could control the degradation mechanism in order to

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produce more controllable products. Hopefully the extension of the results leads to a more useful

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procedure for the pyrolysis of the used tires and the other synthetic rubbers. Hence, we have reported the

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effect of zeolite based catalysts such as used FCC, HZSM-5, mordenite and Ga/FCC - as novel catalyst in

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rubber pyrolysis- on the pyrolysis yield and the composition of the condensed products plus the effect of

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heating rate on the degradation mechanism of SBR using TGA method.

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Energy & Fuels

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2. Experimental

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2.1. Material

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SBR 1502 grade (Styrene: 23.5%) is supplied by Bandar Imam petrochemical company (Mahshahr, Iran),

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Nitrogen gas (purity 99.99%) by Roham Co and used FCC catalyst by Abadan FCC Refinery. The

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Ga(NO3)2 is purchased from Merck chemical. HZSM-5 and mordenite catalysts are supplied by Sudchemi

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Company.

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2.2. Instruments

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2.2.1. Catalyst preparation

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The used FCC catalyst regenerated at 650oC and mild steaming for 4 hours. 0.78g Ga(NO3)2 was

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dissolved in distilled water (100g) under slow stirring at 90oC. The Ga/FCC catalyst was prepared by

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wetness incipient method. The Ga solution was added to the regenerated used FCC (30g) at a lab rotary

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(RV8 model). The rotary temperature and rotation speed were raised step by step up to reach the dried

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mixture. After wetness incipient, the Ga/FCC is dried in an oven at 120oC for 16 hours. Then calcined for

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another 4 hours at 650oC prior to the experiment.

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2.2.2. Analyzing instruments

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The initial used FCC with attention to varied metals in the naphtha had minor content of different metals

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on the surface. Energy dispersive X-ray spectroscope (EDX) is used to detect the metals on used FCC,

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Ga/FCC, HZSM-5 and mordenite catalysts. Meanwhile Si/Al ratio was calculated after Al and Si

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detection using EDX. BET method using Quantachrome Corp. Nova2200, Version 7.11 was used to

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calculate the Surface area of the catalysts.

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A Netzsch TG 209 thermo-balance was used to carry out the thermo-gravimetric analysis (TGA). The

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heating rates of 5, 15, 30, 45 and 90 oC min-1 were used to study the SBR samples. The sample mass was


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12.0-13.0 mg. The TGA experiments were performed in a nitrogen atmosphere (99.99% minimum purity)

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with a flow rate of 30 ml min-1.

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The kinetic parameters, activation energy and pre-exponential factor of SBR pyrolysis were determined

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by the integral method [23]. Many investigators assumed that solid fuel pyrolysis is a first order reaction

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[24–26].

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A gas chromatograph mass spectrometry of model GC–MS-QP5000 was used to identify the varied

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components and carbon number in the condensed products. The analysis was carried out on a 60 m*0.32

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mm capillary column coated with a 1 µm film of DB-1. The oven temperature was programmed, 40 oC

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hold for 10 min to 300 oC at 5 oC min-1 hold for 10 min. The components were identified using the

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NIST12 and NIST62 library of mass spectra and subsets HP G1033A.

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2.2.3. Pyrolysis process

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A 1 L stirred semi-batch reactor (bucchi pilot plant with a custom built reactor) was used to carry out the

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pyrolysis experiments under atmospheric pressure. The schematic diagram of pyrolysis set up is shown in

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Fig. 1. Fragmented SBR rubber (100 g), different catalyst type and amount, stirred speed (50 rpm), carrier

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gas stream (300 ml min-1) and the temperature of 450 oC are the fixed experimental conditions of

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pyrolysis in the reactor. The non-evaporables as coke, the share of gaseous product that condensed in the

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condenser and stored in the glass sampling bottles as the condensed products and the non-condensable

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share of the gaseous product as the non-condensable product are the different product sections. The

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components of total condensed hydrocarbons (residue in the condensers contained C4 to C10+) were

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quantified by GC–MS and the non-condensable products not analyzed. The solid char yield was

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determined gravimetrically after completion of the reaction and the non-condensable yield calculated by

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subtracting the weight of the condensed hydrocarbons and solid products from the sample weight.

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3. Results and discussion

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The structural information of different zeolite based catalyst using the Energy Dispersive X-ray

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spectroscope (EDX) analysis and BET test method are shown in table 1. The results show that Si/Al

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atomic ratio of Ga/FCC zeolite is little different from the used FCC. Petroleum crude oil have varied

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metals content of at least about 5 ppm up to 50 ppm and it resides on the FCC catalyst surface for at least

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about 1% by weight (table 1). It has been reported that the metals on the used FCC can affect on the

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polymer degradation and pyrolysis products [27].

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The mass balance of SBR pyrolysis products (condensable products, solid residue and non-condensable

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by difference) and the composition of condensed products are shown in tables 2–5 for different catalysts

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(used FCC, Ga/FCC, HZSM-5 and mordenite) at catalyst/SBR ratio of 15% and different used FCC

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catalyst/SBR ratios (0–60%). In the following, the degradation trend of SBR using TGA instrument is

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considered.

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3.1. Effect of the different catalysts

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The effect of different zeolite based catalysts on the pyrolysis products is considered in comparison with

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the thermal degradation of SBR in a stirred reactor. Table 2 shows the mass balance data for the thermal

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and catalytic pyrolysis of SBR. Furthermore, the characterization of condensed products using GC–MS as

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a function of catalytic and non-catalytic pyrolysis is given in tables 2 and 3. The reaction products were

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divided into different groups i.e. naphthenes, paraffins, olefins and aromatics. The distribution of C4 to

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C10 and C10+ condensed hydrocarbon products and gasoline range is given in Table 3.

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With and without the catalyst, the main product fraction is condensed product up to 93.2%. Although the

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thermal pyrolysis produced the maximum condensed share in comparison with the catalytic pyrolysis but

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the produced liquid is darker and more viscous. In the catalytic pyrolysis, Ga/FCC produced the most

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condensable liquid and on the opposite side, HZSM-5 produced the least oil –91.5 & 78.7% respectively-.

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The non-catalytic system with 1.6% had minimum coke content and HZSM-5 with 4.3% showed the

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maximum amount though in the compared catalysts, Ga/FCC with 2.5% coke had the better operation. 7 ACS Paragon Plus Environment

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Furthermore, the thermal pyrolysis and Ga/FCC had the lowest share of non-condensable products with

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5.2 and 5.3% respectively and HZSM-5 with 17.0% had the maximum amount. The C5 to C9 fraction as

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the gasoline range had major share in the condensed liquids up to 77.3% using HZSM-5 catalyst though

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without catalyst the gasoline range decreased to 54.4%. The yield of C10+ under thermal pyrolysis system

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with 36.9% is the significant share of condensed product though the zeolite catalysts decreased the C10+

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remarkably.

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The composition of produced condensed liquid using non-catalytic pyrolysis system contained aliphatic

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hydrocarbons (olefins at 38.1% and paraffins at 12.3%) and cyclic hydrocarbons (aromatics at 39.8% and

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naphthenes at 9.8%). The condensed product distributions using Ga/FCC as aromatization catalyst were

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quite different from those by non-catalytic which was characterized as highly selective former of

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aromatics with total yields of 62.1%. The other components are olefins (16. 2%), paraffins (10.3%) and

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naphthenes (11.4%). These results are explained by Diels-Alder reaction mechanism that involves the

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cracking of polymer chains to light hydrocarbons, followed by oligomerization and dehydrocyclization to

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BTXs [28-29].

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With used FCC catalyst, the results are little different from Ga/FCC. The condensed product yield is

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90.4% containing olefins (21.4%), paraffins (14.0%), aromatics (50.3%) and naphthenes (14.3%). While

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with HZSM-5 catalyst, the condensed hydrocarbons decreased in comparison with the other catalysts and

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reached a yield of 78.7%. Aromatics (54.3%), olefins (20.7%), paraffins (13.9%) and naphthenes (11.1%)

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are the main components of the condensed product respectively for this catalyst. The condensed yield of

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mordenite catalyst reached to 85.3%, while the non-condensable yield was to 11.3% and coke to 3.4%.

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By using different catalysts. On the other hand, mordenite had the lowest aromatics amount (43.4%) and

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its olefin, paraffin and naphthenes content were 29.3, 15.5 and 11.8% respectively.

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The results show that the nature of polymer and different catalysts are effective in the type and size of the

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pyrolysis products [10, 15, 30]. Styrene as the main product of catalytic and non-catalytic pyrolysis of

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polystyrene [31] from one side, waxy product and gaseous products plus the condensed oil in the gasoline

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range as the main products of thermal degradation and or catalytic pyrolysis of polyethylene using 8 ACS Paragon Plus Environment

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HZSM-5 [32] and or FCC [10] catalysts respectively from the other side, clearly show the effect of

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polymer and catalyst nature on the pyrolysis products. The different study on the pyrolysis of polyolefins

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shows that HZSM-5 catalyst decreases the condensed products significantly [32] though FCC catalyst and

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the thermal pyrolysis produce the maximum condensed oil. While in the pyrolysis of SBR and PS [31],

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the difference among the condense oil shares using different catalysts and thermal degradation is not too

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significant. It maybe depends on the presence of styrene groups in PS and SBR.

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3.2. Effect of the used FCC catalyst content

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The effect of increasing used FCC to SBR ratio was investigated from 0- 6:10 on the pyrolysis products

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containing condensable, non-condensable and coke (Table 4). The type and amount of catalyst can

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strongly affect the pyrolysis results containing the products share and composition [9-10, 15, 29-30]. The

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results show that the condensed product yield decreased with catalyst increasing from 93.2 to 79.9%.

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Meanwhile coke and non-condensable yields increased with catalyst content from 1.6 to 7.7% and 5.2 to

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12.4% respectively. The increase of coke yield may be attributable to direct relation between

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aromatization and dehydrogenation with the catalyst surface [29-30].

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The second section of Table 4 shows the varied types of condensed fraction as a function of used

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FCC/SBR ratio containing paraffins, naphthenes, olefins and aromatics. The varied components of

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condensed product were olefins (17–39%), paraffins (12–18%), naphthenes (8–15%) and amounts of

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aromatics (39–57%). The rate of Diels-Alder reaction accelerates in the presence of zeolite catalysts and

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the reaction activity increases with the catalyst content in the pyrolysis process [28] though the share of

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styrene in the used SBR grade (1502 grade) is 23.5% and some of the aromatics depend on the nature of

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SBR while the produced aromatics amount is significant and the catalysts and related Diels-Alder reaction

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has effective role in the pyrolysis mechanism.

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As shown in Table 5, the molecular weight of the condensed products decreased mildly when the used

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FCC/SBR ratio increased. However, the yield of gasoline range increased with catalyst content from 54.4

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to 76.0%. Furthermore, in accordance with the results of polyolefin pyrolysis, the size selectively of the

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SBR pyrolysis and gasoline range increases in accordance to the catalyst/polymer ratio [9-10]. 9 ACS Paragon Plus Environment

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3.3. The trend of SBR pyrolysis

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In the case of usual plastics without double bonds and big side group in the structure such as polyethylene

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and polypropylene, the polymer degrades at higher temperatures by increasing the heating rate [13-14].

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While our finding for the pyrolysis of PBR shows a reverse trend and i.e. the chains degrade at lower

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temperatures under fast pyrolysis [15]. The SBR has two main segments containing styrene (plastic) and

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butadiene (rubber) and the SBR pyrolysis acts between rubber and plastic. The weight loss of SBR at

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different heating rates had been investigated using TGA instrument from 150 to 600 ºC. Figures 2& 3

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show the TGA and DTG thermograms of SBR versus temperature at different heating rates (5 to 90 ºC

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min-1). The results show that the DTG curves of slow pyrolysis (5& 15 oC min-1) are different from the

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fast pyrolysis (45& 90 oC min-1). The slow pyrolysis curves tend to behave under mono-modal peak while

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the fast pyrolysis of SBR (specially 90 oC min-1) shows the obvious bimodal peak. This is in a condition

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that the first peak of the curve happens at lower temperatures in comparison with the slow pyrolysis. It

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seems that the pyrolysis mechanisms and their shares are under the influence of the different bonds in

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SBR chains such as the double bonds and phenyl groups. Under low heating rates, the double bonds and

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low given energy –consistent for degrading the π bonds at low temperatures– can prepare a proper media

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for crosslink mechanism and the phenyl groups follow the chain scission mechanism. While at fast

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pyrolysis (90 oC min-1), the high given energy prevents the 3-D nets creation under the crosslink

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mechanism and on the other hand, the chain scission and un-zipping mechanisms as the main degradation

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mechanisms create the bimodal DTG curve of degradation.

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As can be seen in the Fig. 2, the degradation curves of SBR under different heating rates have three steps

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containing initial, medium and termination steps. In the initial step from 0 to ~10% conversion, the chain

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scission mechanism affects on the weight loss trend and like the usual plastic, SBR degrades at higher

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temperatures under increasing the heating rate. Simultaneously in this step, the crosslink mechanism is

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creating the 3-D nets though the activity of the mechanism decreases by increasing the heating rate. The

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effect of created 3-D nets is seen in the medium step. In the medium step (Conversion: ~10-50%), for


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slow pyrolysis (5& 15 oC min-1) at the temperature range of ~ 280-350 oC, the polymer resists degradation

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and the created nets tend to degrade at higher temperatures though the other mechanisms containing chain

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scission and un-zipping are effective in the degradation and at the higher temperatures (> 350 oC). In the

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medium step, the fast pyrolysis as free crosslink thermograms (90 oC min-1) indicates a strange trend –

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like PBR [15] - and degrades at lower temperatures in comparison with the slow pyrolysis. The first peak

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of the DTG curves indicates the difference between the effective mechanisms under different heating

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rates. The slow pyrolysis using created 3-D nets prevent the degradation and the first peak isn’t seen

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while the fast pyrolysis (45 & 90 oC min-1) under un-zipping and chain scission mechanisms show the

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obvious peak in the medium step. In the termination step (conversion: 50% up to end), for all of the

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heating rates, the chain scission and un-zipping are the main mechanisms and in the termination step like

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the usual plastics, SBR degrades at higher temperatures under increasing the heating rate.

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Fig. 4 shows the typical plots of ln [−ln (1−x) /T2] versus 1/T, indicating that for all of the heating rates,

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three independent first order reactions could be used to describe the pyrolysis process. Table 6 lists the

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activation energies are obtained by different heating rates in a similar expression to that used by other

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workers [23-26]. The results indicate that activation energy is decreased by increasing of heating rate

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though the activation energy under heating rate show the significant decrease in comparison with the

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others (154.7-131.5 kJ mol-1).

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4. Conclusion

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The pyrolysis of SBR using a laboratory catalytic stirred reactor and TGA instrument has been studied.

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The pyrolysis products yield and the condensed product distribution due to the different catalysts such as

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Gallium promoted used FCC, used FCC, HZSM-5, Mordenite and without catalyst plus the different ratio

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of used FCC/SBR from 0 to 60% have been considered.

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In the characteristics of the condensed products, the main products obtained were light hydrocarbons

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within the range of gasoline components. Generally, the pyrolysis of SBR with 23.5% styrene content

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produces a significant amount of aromatics, although with different catalysts, the aromatic contents is

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changed remarkably. The Ga/FCC catalyst with high share of condensable and aromatics can be a useful

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catalyst in the pyrolysis of SBR and the other rubbers.

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The results show that the special structure of SBR composed of Styrene and Butadiene (double bond)

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randomly positioned in the main chin of the SBR can affect the degradation mechanism under different

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heating rates. Styrene follow the chain scission and end-zipping and the double bonds tend to prepare the

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3-D nets under crosslink mechanism. The degradation trend of SBR is between the polyolefin and PBR

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trends. The results show that heating rate can play an important role in rubber degradation and with

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attention to PBR and SBR degradation, increasing the heating rate can decrease the required energy for

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the pyrolysis of rubber wastes.

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5. References

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[1] Islam MR, Islam MN, Mustafi NN, Rahim MA, Haniu H. Thermal Recycling of Solid Tire Wastes for

292

Alternative Liquid Fuel: The First Commercial Step in Bangladesh. Proce Eng 2013; 56: 573–82.

293

[2] Wu X, Wang Sh, Dong R. Lightly pyrolyzed tire rubber used as potential asphalt alternative. Cons

294

Buil Mater 2016; 112: 623–8.

295

[3] Martínez JD, Puy N, Murillo R, García T, Navarro MV, Mastral AM. Waste tyre pyrolysis – A

296

review. Rene Sust Ener Revi 2013; 23: 179–213.

297

[4] Grieco E, Bernardi M, Baldi G. Styrene–butadiene rubber pyrolysis: Products, kinetics, modelling. J

298

Anal Appl Pyrol 2008; 82(2): 304–11.

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[5] Ayloń E, Calleń MS, Lo´ pez JM, Mastral AM. Assessment of tire devolatilization kinetics. J Anal

300

Appl Pyrol 2005; 74: 259–64.

301

[6] Islam MR, Haniu H, Alam Beg MR. Liquid fuels and chemicals from pyrolysis of motorcycle tire

302

waste: product yields, compositions and related properties. Fuel 2008; 87: 3112–22.

303

[7] Murillo R, Navarro MV, Stelmach S. Effect of acid catalysts on scrap tyre pyrolysis under fast heating

304

conditions. J Anal Appl Pyrol 2008; 82: 199–204.

305

[8] Leung DYC, Wang CL. Kinetic study of scrap tyre pyrolysis and combustion. J Anal Appl Pyrol

306

1998; 45: 153–69.

307

[9] Abbas-Abadi MS, Haghighi MN, Yeganeh H. The effect of temperature, catalyst, different carrier

308

gases and stirrer on the produced transportation hydrocarbons of LLDPE degradation in a stirred reactor. J

309

Anal Appl Pyrol 2012; 95: 198–204.

310

[10] Abbas-Abadi MS, Haghighi MN, Yeganeh H. Evaluation of pyrolysis product of virgin high density

311

polyethylene degradation using different process parameters in a stirred reactor. Fuel Process Technol

312

2012; 109: 90–5.

313

[11] Zhou Q, Wang Y-Zh, Tang Ch, Zhang Y-H. Modifications of ZSM-5 zeolites and their applications

314

in catalytic degradation of LDPE. Polym Degrad Stab 2003; 80: 23–30. 13 ACS Paragon Plus Environment

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

Page 14 of 25

315

[12] Cullis CF, Hirschler MM. The combustion of organic polymers. Oxford: Clarendon Press; 1981.

316

[13] Abbas-Abadi MS, Haghighi MN, Yeganeh H, Bozorgi B. The effect of melt flow index, melt flow

317

rate, and particle size on the thermal degradation of commercial high density polyethylene powder. J

318

Therm Anal Calorim 2013; 114(3): 1333–9.

319

[14] Abbas-Abadi MS, Haghighi MN, Yeganeh H. Effect of the melt flow index and melt flow rate on the

320

thermal degradation kinetics of commercial polyolefins. J Appl Polym Sci 2012; 126: 1739–45.

321

[15] Salmasi SS, Abbas-Abadi MS, Haghighi MN, Abedini H. The effect of different zeolite based

322

catalysts on the pyrolysis of poly butadiene rubber. Fuel 2015; 160: 544–8.

323

[16] Yang M, Shibasaki Y. Mechanisms of thermal degradation of polystyrene, polymethacrylonitrile,

324

and their copolymers on flash pyrolysis. J Polym Sci 1998; 36: 2315-30.

325

[17] Muenpol S, Jitkarnka S. Effects of Fe supported on zeolites on structures of hydrocarbon compounds

326

and petrochemicals in waste tire-derived pyrolysis oils. J Anal Appl Pyrol 2016; 117: 147–56.

327

[18] Danon B, Gryp PV, Schwarz CE, Görgens JF. A review of dipentene (dl-limonene) production from

328

waste tire pyrolysis. J Anal Appl Pyrol 2015; 112: 1–13.

329

[19] Leng Sh, Wang X, Wang J, Liu Y, Ma F, Zhong X. Waste Tire Pyrolysis for the Production of Light

330

Hydrocarbons over Layered Catalysts. Ener tech 2015; 3(8): 851–5.

331

[20] Witpathomwong Ch, Longloilert R, Wongkasemjit S, Jitkarnka S, Improving Light Olefins and Light

332

Oil Production Using Ru/MCM-48 in Catalytic Pyrolysis of Waste Tire. Ener Proced 2011; 9: 245–51.

333

[21] Arabiourrutia M, Olazar M, Aguado R, López G, Barona A, Bilbao J. HZSM-5 and HY Zeolite

334

Catalyst Performance in the Pyrolysis of Tires in a Conical Spouted Bed Reactor. Ind Eng Chem Res

335

2008; 47 (20): 7600–9.

336

[22] Khowatimy FA, Priastomo Y, Febriyanti E, Riyantoko H, Trisunaryanti W. Study of Waste

337

Lubricant Hydrocracking into Fuel Fraction over the Combination of Y-Zeolite and ZnO Catalyst. Proced

338

Envi Sci 2014; 20: 225–34.

339


Page 15 of 25

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

340

[23] Ying GP, Enrique V, Luis P. Pyrolysis of blends of biomass with poor coals. Fuel 1996; 75(4): 412–

341

8.

342

[24] Mustafa VK, Esber O, Ozgen K, Cahit H. Effect of particle size on coal pyrolysis. J Anal Appl Pyrol

343

1998; 45: 103–10.

344

[25] Zhou L, Wang Y, Huang Q, Cai J. Thermogravimetric characteristics and kinetic of plastic and

345

biomass blends co-pyrolysis. Fuel Proc Tech 2006; 87: 963–9.

346

[26] Senneca O, Salatino P, Chirone R. A fast heating-rate thermogravimetric study of the pyrolysis of

347

scrap tyres. Fuel 1999; 78:1575–81.

348

[27] Lee KH, Shin DH. Catalytic degradation of waste polyolefinic polymers using spent FCC catalyst

349

with various experimental variables. Kore J Chem Eng 2003; 20(1): 89-92.

350

[28] Cheng YT, Huber GW. Production of targeted aromatics by using Diels–Alder classes of reactions

351

with furans and olefins over ZSM-5. Green Chem 2012; 14: 3114-25.

352

[29] Abbas-Abadi MS, McDonald AG, Haghighi MN, Yeganeh H. Estimation of pyrolysis product of

353

LDPE degradation using different process parameters in a stirred reactor. Polyolefins J 2015; 2(1): 39-47.

354

[30] Abbas-Abadi MS, Haghighi MN, Yeganeh H, McDonald AG. Evaluation of pyrolysis process

355

parameters on polypropylene degradation products. J Anal Appl Pyrol 2014; 109: 272–7.

356

[31] Puente G, Sedran U. Recycling polystyrene into fuels by means of FCC: performance of various

357

acidic catalysts. Appl Cat B Env 1998; 19: 305-11.

358

[32] Marcilla A, Beltrań MI, Navarro R. Thermal and catalytic pyrolysis of polyethylene over HZSM5

359

and HUSY zeolites in a batch reactor under dynamic conditions. 2009; 86: 78–86.

360

361


Energy & Fuels

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Fig 1: Flow scheme of the pyrolysis system

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Fig 2: TGA curves of SBR at different heating rates (5, 15, 30, 45 and 90 oC min-1)

370

371

372

373

374

375


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376 377

Fig 3: DTG curves of SBR at different heating rates (5, 15, 30, 45 and 90oC min-1)

378

379

380

381

382

383

384

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389 390

Fig 4: Plot of ln(−ln(1−x) /T2) vs 1/T of SBR at different heating rates

391

392

393

394

395

396

397


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398

Page 20 of 25

Table 1: The specification of different catalysts used in the catalytic degradation of SBR

catalyst

Used FCC

Ga/FCC

HZSM-5

Mordenite

235

215.2

381.3

449.1

Si/Al

6

5.9

20

20

Ga (%)

0

0.82

0

0

Na (%)

0.3

0.29

0.18

0.11

Ca (%)

1.54

1.52

0

0

Fe (%)

0.2

0.19

0

0

V(ppm)

450

435

0

0

Ni(ppm)

180

175

0

0

Surface Area (m2 g-1)

399

400

401

402

403

404

405

406

407

408

409


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Energy & Fuels

Table 2: The effect of different catalysts on the SBR products yield and the condensed product

catalyst

Liquid (%)

Gas (%)

Coke (%)

olefins paraffins naphthenes aromatics (%) (%) (%) (%)

no catalyst

93.2

5.2

1.6

38.1

12.3

9.8

39.8

used FCC

90.4

7.1

2.5

21.4

14

14.3

50.3

Ga/FCC

91.5

5.3

3.2

16.2

10.3

11.4

62.1

HZSM-5

78.7

17

4.3

20.7

13.9

11.1

54.3

3.4

37.3

17.5

12.8

32.4

Mordenite

85.3 11.3

412

413

414

415 416 417 418 419 420 421 422


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424

Table 3: The effect of different catalysts on the carbon number distribution of the SBR condensed product

425

composition

carbon number

0

used FCC

Ga/FCC

HZSM-5

Mordenite

C4

1.3

0.7

0.6

3.6

0.7

C5

2.4

1.8

1.7

3.8

1.4

C6

8.8

15.5

14.8

29.5

4.6

C7

11.7

14

17.9

12.6

18.6

C8

22.4

20.7

22.3

15.2

20.1

C9

9.1

20.4

18.2

16.2

31.5

C10

7.4

11.5

10.8

7.1

11.4

C10+ gasoline range

36.9

15.4

13.7

12

11.7

54.4

72.4

74.9

77.3

76.2

426 427 428 429 430 431 432 433 434 435 436 437 438


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439

Energy & Fuels

Table 4: The effect of used FCC/SBR ratio on the SBR product yield and liquid composition Used FCC/SBR Liquid (%)

Gas

Coke

olefins (%)

paraffins naphthenes aromatics (%) (%) (%)

0

93.2

5.2

1.6

38.1

12.3

9.8

39.8

15

90.4

7.1

2.5

21.4

14

14.3

50.3

30

86.1

9.6

4.3

19.1

14.7

13

53.2

45

82.5

11.9

5.6

19.4

16.2

8.7

55.7

60

79.9

12.4

7.7

17.9

17.1

8.9

56.1

440 441 442 443 444 445 446 447 448 449 450 451 452 453


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454

Table 5: The effect of used FCC/SBR ratio on the carbon number distribution of the SBR condensed

455

product composition

Carbon 0

15

30

45

60

C4

1.3

0.7

0.6

0.5

0.5

C5

2.4

1.8

2.3

2.7

2.9

C6

8.8

15.5

15.3

15.9

16

C7

11.7

14

16.4

18.2

19.3

C8

22.4

20.7

19.8

18.9

19.1

C9

9.1

20.4

19.5

19.8

18.7

C10

7.4

11.5

12.1

10.9

10.6

C10+

36.9

15.4

14

13.1

12.9

sum(C5-C9)

54.4

72.4

73.3

75.5

76.0

Number

456 457 458 459 460 461 462 463 464 465


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Energy & Fuels

Table 6: The effect of heating rate on the activation energy of SBR degradation

heating rate (oC min-1)

Activation Energy (KJ mol-1)

5

154.7

15

152.8

30

149.1

45

146.4

90

131.5

467 468 469 470


The Consideration of Different Effective Zeolite Based Catalysts and

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