Upgrading of aspen poplar wood oil over HZSM-5 zeolite catalyst

Thermally fractionated components of an oil prepared by the liquefaction of aspen poplar wood have been upgraded using a HZSM-5 zeolite catalyst to yield products rich in benzene, toluene, xylenes and higher molecular weight aromatics. The effect of reactor temperatures on the relative abundance of these products has been studied.     

HAL型重芳烃轻质化催化剂研究及应用前景

HAL是一种含贵金属和ZSM-5沸石的双功能催化剂,可将催化重整、歧化和异构化反应尾油以及加氢汽油中所含的C_9以上烷基芳烃经催化反应制取苯、甲苯和二甲苯。该催化剂具有较高的活性、活性稳定性和较低的耗氢量。研究发现反应温度、压力、空速以及氢油比对催化剂的反应性能有影响,并确定了最佳反应条件。成功地进行了中型试验,BTX单程收率可达36％～50％。根据中型试验结果,设计了重质芳烃轻质化的基本工艺流程。     

The influence of catalyst regeneration on the composition of zeolite-upgraded biomass pyrolysis oils

The composition of oils derived from the on-line, low pressure zeolite upgrading of biomass pyrolysis oils from a fluidized bed pyrolysis unit have been investigated in relation to the regeneration of the zeolite catalyst. The catalyst used was H-ZSM-5 zeolite. The gases were analysed by packed column gas chromatography. The composition of the oils before catalysis and after catalyst upgrading were analysed by liquid chromatography fractionation, followed by coupled gas chromatography—mass spectrometry of each fraction. In particular, the aromatic and oxygenated aromatic species were identified and quantified. In addition, the oils were analysed for their elemental composition and molecular weight range using size exclusion chromatography. Before catalysis the biomass pyrolysis oil was highly oxygenated but after catalysis a highly aromatic oil was formed with high concentrations of monocyclic aromatic hydrocarbons. In addition, significant concentrations of polycyclic aromatic hydrocarbons (PAH) were formed. Regeneration of the zeolite catalyst showed that continued regeneration reduced the effectiveness of the catalyst in converting biomass pyrolysis oils to an aromatic product. Elemental analysis of the upgraded oils showed an increase in the oxygen content of the oil with increasing regeneration of the catalyst. The molecular weight range of the oils was found to decrease markedly after catalysis, but continued regeneration of the catalyst increased the molecular weight range of the upgraded oils. Detailed analysis of the uncatalysed oils showed they contained low concentrations of aromatic and PAH species which markedly increased in concentration after catalysis. The overall effect of increasing catalyst regeneration was a decrease in the concentration of aromatic hydrocarbons and PAH. Also as the catalyst was regenerated, the number of methyl groups on the parent single ring aromatic compound or PAH increased. The oxygenated aromatic species in the oil before catalysis were mainly, phenols and benzenediols and their alkylated homologues. After catalysis some of the oxygenated species were reduced and some increased in concentration. A dual mechanistic route is suggested for the formation of aromatics and PAH during the catalytic upgrading of biomass pyrolysis oils: (1) the formation of low-molecular-weight hydrocarbons on the catalyst which then undergo aromatization reactions to produce aromatic hydrocarbons and PAH; (2) deoxygenation of oxygenated compounds found in the non-phenolic fraction of the pyrolysis oils which directly form aromatic compounds.     

Temperature selective condensation of tyre pyrolysis oils to maximise the recovery of single ring aromatic compounds

Scrap tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a condenser system maintained at separately controlled temperature to determine the yield and composition of the condensed oil. The main objective was to maximise the selective condensation of single ring aromatic compounds which are of known higher commercial value. In addition, the molecular weight range of the condensed oils was also determined. The influence of condenser packing material was also examined. The results showed that the type of packing material within each condenser was also examined and found to be important in determining the yield and composition of the condensed oil. Similarly, condenser temperatures determined the yield and also composition of the oils. Maximum concentrations of single ring aromatic compounds in relation to the selective condensation process showed significant increases in the concentration of certain compounds could be achieved in the condensed oils collected in each condenser.     

The pyrolysis of scrap automotive tyres: The influence of temperature and heating rate on product composition

Shredded automotive tyre waste was pyrolysed in a 200 cm³ static batch reactor in a N₂ atmosphere. The compositions and properties of the derived gases, pyrolytic oils and solid char were determined in relation to pyrolysis temperatures up to 720 °C and at heating rates between 5 and 80 °C min⁻¹. As the pyrolysis temperature was increased the percentage mass of solid char decreased, while gas and oil products increased until 600 °C after which there was a minimal change to product yield, the scrap tyres producing approximately 55% oil, 10% gas and 35% char. There was a small effect of heating rate on the product yield. The gases were identified as H₂, CO, CO₂, C₄H₆, CH₄ and C₂H₆, with lower concentrations of other hydrocarbon gases. Chemical class composition analysis by liquid chromatography showed that an increase in temperature produced a decrease in the proportion of aliphatic fractions and an increase in aromatic fractions for each heating rate. The molecular mass range of the oils, as determined by size exclusion chromatography, was up to 1600 mass units with a peak in the 300–400 range. There was an increase in molecular mass range as the pyrolysis temperature was increased. FT-i.r. analysis of the oils indicated the presence of alkanes, alkenes, ketones or aldehydes, aromatic, polyaromatic and substituted aromatic groups. Surface area determination of the solid chars showed a significant increase with increasing pyrolysis temperature and heating rate.     

喷动-载流床中Co/ZSM-5分子筛催化剂对煤热解的催化作用

在喷动-载流床中考察了Co/ZSM-5分子筛催化剂对煤热解气、液、固产物产率及组成变化的影响,分析了催化剂失活的原因及催化剂的再生使用寿命. 结果表明,在550~600℃的热解温度范围内,Co/ZSM-5分子筛催化剂提高煤热解总转化率达70%以上. 而在650℃时,煤热解正己烷可溶物产率最大,其中酚类、脂肪烃类和芳香烃类的产率比无催化剂时分别增加203%, 51%和78%. 因积碳失活的Co/ZSM-5分子筛催化剂经过500℃焙烧后再生使用6次,活性下降不到5%. Co/ZSM-5分子筛催化剂的结构表征结果说明,Co进入了ZSM-5分子筛骨架. Co的催化加氢活性促进了H·与煤热解焦油片断的结合,减少了焦油聚合成大分子的几率,从而提高了煤热解油品的产率和品质.     

Catalytic pyrolysis of woody biomass in a fluidized bed reactor: Influence of the zeolite structure

Catalytic pyrolysis of biomass from pine wood was carried out in a fluidized bed reactor at 450 °C. Different structures of acidic zeolite catalysts were used as bed material in the reactor. Proton forms of Beta, Y, ZSM-5, and Mordenite were tested as catalysts in the pyrolysis of pine, while quartz sand was used as a reference material in the non-catalytic pyrolysis experiments. The yield of the pyrolysis product phases was only slightly influenced by the structures, at the same time the chemical composition of the bio-oil was dependent on the structure of acidic zeolite catalysts. Ketones and phenols were the dominating groups of compounds in the bio-oil. The formation of ketones was higher over ZSM-5 and the amount of acids and alcohols lower than over the other bed materials tested. Mordenite and quartz sand produced smaller quantities of polyaromatic hydrocarbons than the other materials tested. It was possible to successfully regenerate the spent zeolites without changing the structure of the zeolite.     

轻烃催化裂解制低碳烯烃反应规律与原料特征化

利用小型固定床实验装置对比研究了轻烃模型化合物的催化裂解性能,从优到劣的顺序依次是正构烯烃、正构烷烃、环烷烃、异构烷烃、芳香烃。正构烷烃、异构烷烃与环烷烃催化裂解的总低碳烯烃收率有较大差别,但是总低碳烯烃选择性却均在56.57%左右。研究了直馏石脑油的催化裂解性能,发现乙丙烯收率和总低碳烯烃收率随反应温度的升高及重时空速的降低而逐渐增大;在反应温度680℃、重时空速4.32 h^-1和水油稀释比0.35的条件下,乙丙烯收率35.87%（质量）,总低碳烯烃收率为41.94%（质量）。针对轻烃催化裂解提出了原料特征化参数KF,它是原料H/C原子比、相对密度与分子量的函数,能较好地表征轻烃原料的催化裂解性能。     

Conversion of heavy reformate into xylenes over mordenite-based catalysts

The conversion of heavy reformate into high-value xylenes was studied over a series of H-mordenite-based catalysts in a fluidized-bed reactor at 400 °C. The results show that methyl-ethyl-benzenes (MEBs) were more reactive than trimethylbenzenes (TMBs) over all the catalysts studied. Mordenite catalyst with higher acid site concentration (M1) favored dealkylation of MEBs while another mordenite catalyst with lower acid site concentration (M2) favored disproportionation of TMBs. Mixing M2 with ZSM-5 (M2Z1) enhanced MEBs conversion (69.2%) and xylenes yield (22.5 wt.%). The conversion of heavy reformate and toluene mixtures over M2Z1 catalyst increased xylenes yield to a maximum at 25.3 wt.% for a feed containing 70:30 heavy reformate and toluene. The results of converting mixtures of 1,2,4-TMB/toluene and heavy reformate/toluene indicate that catalyst acid site concentration plays a key role in promoting desirable transalkylation reactions needed to enhance xylenes yield. The amount of coke formed increased with the acid site concentration of catalysts and more coke laydown was observed during conversion of heavy reformate than 1,2,4-TMB.     

Promoting Xylene Production in Benzene Methylation using Hierarchically Porous ZSM-5 Derived from a Modified Dry-gel Route

Methylation of benzene is an alternative low-cost route to produce xylenes, but selectivity to xylene remains low over conventional zeolitic catalysts. In this work, a combined dry-gel-conversion and s...     

SYNTHESIS OF ZSM-5 FROM MODIFIED CLINOPTILOLITE AND ITS CATALYTIC ACTIVITY IN ALKYLATION OF BENZENE TO ETHYLBENZENE

ZSM-5 catalysts were prepared by utilizing clinoptilolite found in Western Anatolia in abundant amounts as a type of natural zeolite. Hydrothermal reaction was conducted with HCl-treated clinoptilolite at 180°C. After characterizing the solid products obtained by this reaction as ZSM-5 by means of XRD, IR, TGA, surface area analyzer, and chemical analysis they were tested as catalysts in benzene alkylation reaction with ethylene leading to ethylbenzene. Catalytic performance of samples prepared in this study was investigated for benzene conversion, ethylbenzene yield, and selectivity. It was found that ZSM-5(A) sample showed performance similar to that of the reference sample (ZSM-5(C)) synthesized by using patented literature information in terms of benzene conversion. When the reaction temperature was increased from 400° to 425°C ethylbenzene yield and selectivity results of ZSM-5(A) sample were improved but coke formation increased. Catalyst test results indicated the possibility of using clinoptilolite as a raw material in the synthesis of ZSM-5 catalyst for alkylation of benzene with ethylene reaction.     

含油污泥在ZSM-5沸石上催化热解产物特性

采用U型固定床管式炉研究了含油污泥在ZSM-5分子筛催化剂上的热解产物特性。发现在450℃下未使用催化剂热解时,GC-MS和GC测得的油泥热解油产物中的主要成分为烷烃和烯烃,芳烃含量较低;气体产物中主要为短链烃类,氢气产量较少。而在ZSM-5分子筛的催化作用下,热解油中芳香烃产量达到88.4%,气体产物中的氢气产量和短链烃类产量均明显增加。研究了400～550℃之间分子筛对含油污泥的催化效果,发现ZSM-5在500℃时催化效果最佳,油相产率达到65.6%,油相中的沥青质和胶质含量较低,芳香烃产量达到90.9%。通过热重和XPS分析发现分子筛上的积炭主要以多环芳烃焦炭的形式存在。     

Conversion of vegetable oils under conditions of catalytic cracking

The effect of the composition of zeolite containing catalyst, the conditions of conducting the process, and the nature of oils on the distribution of target products during conversion under conditions of catalytic cracking is studied. The study is performed on bizeolite catalysts containing zeolites (ultrastable Y and ZSM-5 at different ratios) and on catalyst LUX containing18 wt % of zeolite Y in the HREY form. It is shown that the presence of zeolite ZSM-5 in the catalyst composition promotes the formation of olefines C₂–C₄. An increase in the severity of cracking process (elevated temperatures and catalyst: raw material ratios) improves the yield of gaseous products and coke with a simultaneous reduction in the yield of the gasoline fraction. The effect the nature of vegetable oils has is studied using the examples of palm, rapeseed, mustard, and sunflower oils. It is demonstrated that for the maximum yield of olefines C₂–C₄ and gasoline, we must use oils with elevated contents of saturated fatty acids. The regularities of the simultaneous cracking of sunflower oil and vacuum gas oil are studied. It is been found that upon simultaneous cracking, the total conversion of the mixed feedstock and yield of gasoline fraction increase; the maximum effect is attained with the addition of 3–10 wt % of vegetable oil.     

Upgrading of derived pyrolysis vapors for the production of biofuels from corncobs

A bubbling fluidized bed pyrolyzer was integrated with an in-situ honeycomb as a catalytic upgrading zone for the conversion of biomass to liquid fuels. In the upgrading zone, zeolite coated ceramic honeycomb (ZCCH) catalysts consisting of ZSM-5 (Si/Al=25) were stacked and N₂ or recycled non-condensable gas was used as a carrier gas. Ground corncob particles were fast pyrolyzed in the bubbling bed using fine sand particles as a heat carrier and the resulting pyrolysis vapors were passed on-line over the catalytic upgrading zone. The influence of carrier gas, temperature, and weight hourly space velocity (WHSV) of catalyst on the oil product properties, distribution and mass balance were studied. Using ZCCH effectively increased the hydrocarbon yield and the heating value of the dry oil, especially in the presence of the recycled noncondensable gas. Even a low usage of zeolite catalyst at WSHV of 180 h⁻¹ was effective in upgrading the pyrolysis oil and other light olefins. The highest hydrocarbon (≥C2) and liquid aromatics yields reached to 14.23 and 4.17 wt-%, respectively. The undesirable products including light oxygenates, furans dramatically decreased in the presence of the ZCCH catalyst.     

On the use of infrared spectroscopy in the study of carbon dioxide decomposition on copper containing methanol synthesis catalysts

A novel and convenient procedure for the catalytic acylation of a series of aromatic compounds such as benzene, toluene, xylenes (o-, m-, p-), mesitylene, isopropylbenzene and N,N-dimethylaniline to the corresponding ketones using medium- and large-pore zeolites as catalyst and acetic acid or acetyl chloride as acylating agent at different reaction temperatures in a tubular reactor is demonstrated for the first time. The H-ZSM5 and H-beta zeolite catalysts exhibited the higher turnover rates (TOF× 10^-3 s^-1 mol^-1 Al) for the acetic acid or acetyl chloride conversion to the products. In some cases, nearly total conversion of acylating agent with very high selectivity to the para product is achieved. It is found that the reactivity of the aromatic compounds increases with the increase of -CH₃ groups in the benzene ring. Mechanistically, it is assumed that an active species (CH₃CO⁺) is generated catalytically from the acylating agent by an acidic zeolite which attacks the aromatic ring and produces corresponding aromatic ketones.     

Production of Xylenes from Toluene and 1,2,4‐Trimethylbenzene over ZSM‐5 and Mordenite Catalysts in a Fluidized‐Bed Reactor

The production of various xylenes from toluene, heavy aromatics such as 1,2,4‐trimethylbenzene (1,2,4‐TMB) and their mixture was investigated over H‐ZSM‐5 (H‐Z), H‐mordenite (H‐M) and a dual zeolitic catalyst comprising ZSM‐5 and mordenite (H‐ZM). The experiments were conducted in a riser‐simulator reactor under different operating conditions to study the effect of temperature, reaction time and feed composition on conversion and product yields. At 400 °C, the conversion of toluene over the three catalysts yielded mainly benzene and xylenes with maximum conversion at 25 % and a xylene yield of 12.5 wt % over the H‐M catalyst. The transformation of 1,2,4‐TMB doubled the conversion level and xylene yield and suppressed benzene formation. However, a considerable portion of the 1,2,4‐TMB feed was isomerized into 1,2,3‐TMB and 1,3,5‐TMB accompanied by the formation of tetramethylbenzenes (TeMBs). The conversion of an equimolar mixture of toluene and 1,2,4‐TMB over the three catalysts resulted in higher toluene conversion and double xylene yield in comparison with 1,2,4‐TMB alone. The advantage of using a dual zeolitic catalyst was observed at an equimolar feed of toluene and 1,2,4‐TMB, exhibiting maximum toluene conversion, higher xylene yield and the formation of lower levels of undesirable products.     

Rapid and catalytic pyrolysis of corn stalks

Non-catalytic and catalytic rapid pyrolysis of corn stalks was studied in a tubular fixed-bed reactor. The optimum operating conditions giving the highest liquid yield was determined as pyrolysis temperature of 500 °C, sweeping gas flow rate of 400 cm³ min^− 1 and heating rate of 500 °C min^− 1. In the catalytic process, rapid pyrolysis of stalks was performed at the optimum conditions with catalysts such as ZSM-5, HY and USY. The highest liquid yield from the catalytic pyrolysis was 27.55% with ZSM-5, while the oil from non-catalytic pyrolysis was 33.30%. In the last part, various spectroscopic and chromatographic methods were applied for characterization of bio-oils. Although catalytic pyrolysis converts the long chains of alkanes and alkenes of the oils into lower weight hydrocarbons, the obtained oil yields were lower than those of non-catalytic pyrolysis. USY catalyst gives the highest amount of aromatics among the catalysts used. Moreover, TG–DTA analyses were applied on raw materials to investigate thermal degradation of corn stalks and calculate the kinetic parameters.     

Improving hydrocarbons production via catalytic co-pyrolysis of torrefied-biomass with plastics and dual catalytic pyrolysis

To increase the low yield and selectivity of aromatic hydrocarbons during the biomass pyrolysis process, we torrefied the biomass and then co-pyrolyzing with plastics such as high-density polyethylene (HDPE), polystyrene (PS), ethylene-vinyl acetate (EVA) and polypropylene (PP) and also single and dual catalyst layouts were investigated by Py-GC/MS. The results showed that non-catalytic fast pyrolysis (CFP) of raw bagasse (RBG) generated no aromatics. After torrefaction non-CFP of torrefied bagasse (TBG) generated low aromatic yield. Indicating that torrefaction would enhance the proportion of aromatics during the pyrolysis process. The CFP of TBG_200℃ and TBG_240℃ over ZSM-5 produced the total aromatic yield of 1.96 and 1.88 times higher, respectively, compared to non-CFP of TBG. Furthermore, the addition of plastic could increase H/Ceff ratio of the mixture, consequently, increase the yield of aromatic compounds. Among the various torrefied-bagasse/plastic mixtures, the CFP of TBG/EVA (7:3 ratio) mixture generated the highest the total aromatic yield of 7.7 times more than the CFP of TBG alone. The dual catalyst layout could enhance the yield of aromatics hydrocarbons. The dual-catalytic co-pyrolysis of TBG_200℃/plastic (1:1) ratio over USY (ultra-stable Y zeolite)/ZSM-5, improved the total aromatics yield by 4.33 times more than the catalytic pyrolysis of TBG_200oC alone over ZSM-5 catalyst. The above results showed that the yield and selectivities of light aromatic hydrocarbons can be improved via catalytic co-pyrolysis and dual catalytic co-pyrolysis of torrefied-biomass with plastics.     

生物质模化物催化热解制取烯烃和芳香烃

采用愈创木酚作为生物质模型化合物,以ZSM-5为催化剂,在固定床反应器中研究了反应温度、质量空速以及分压对热解产物产率、选择性的影响,并考察了催化剂的积炭情况。结果表明,愈创木酚催化热解的主要产物为酚类,其次是芳香烃。温度对产物分布有显著影响。催化剂适量的积炭有利于提高烯烃和芳香烃的产率。根据愈创木酚催化热解反应产物分布,推测其主要反应为脱除甲氧基形成酚类,进一步芳构化形成芳香烃。本文研究结果为研究生物质催化热解反应机理提供了理论依据。     

乙基环己烷催化裂解制低碳烯烃反应动力学

利用小型固定床实验装置研究了乙基环己烷在基于ZSM-5分子筛介孔催化剂上的裂解性能,发现乙基环己烷具有较好的裂解性能,原料转化率在80%以上,乙丙烯收率（质量分数）可达41%,低碳烯烃收率（质量分数）接近50%,液体产物主要是苯、甲苯、二甲苯等芳香烃。同时考虑乙基环己烷催化裂解过程中的热反应与催化反应,建立了包含14个反应的动力学模型。基于4个反应温度下的裂解实验数据,求取了反应动力学模型的参数。求得的表观活化能均在90 kJ·mol^-1以下,主要组分收率的模型预测值与实验值的平均相对误差不高于10%。