Catalyst for Increasing Ethylene and Propylene Production and Its Industrial Application in a Catalytic Pyrolysis Unit

Light olefins,particularly ethylene and propylene,are the most important building blocks for the petrochemical industry,and demand for their production has been increasing.The catalytic pyrolysis process(CPP)and the corresponding catalyst,developed by SINOPEC Research Institute of Petroleum Processing Co.,Ltd.,are designed to maximize the light olefin yield from catalytic cracking of heavy feedstocks.However,owing to the continuing degradation of feedstocks,the original catalyst can no longer maintain its activity.Herein,we describe the rational design of the new catalyst,Epylene,from a new metal-modified hierarchical ZSM-5 zeolite and matrix.Epylene was tested in the CPP unit of Shaanxi Yanchang Coal Yulin Energy and Chemical Company.A test run and base run were conducted to demonstrate the better performance of Epylene compared with the original catalyst.The properties of the feedstocks and the operating conditions in both runs were similar.The light olefin yield was increased from 33.95%to 36.50%and the coke yield was only 9.58%in the test run,which was lower than that in the base run.

Reaction characteristics of maximizing light olefins and decreasing methane in C_(5) hydrocarbons catalytic pyrolysis

When converting C_(5) hydrocarbons to light olefins by catalytic pyrolysis,the generation of low value-added methane will affect the atomic utilization efficiency of C_(5) hydrocarbons.To improve the atomic utilization efficiency,different generation pathways of light olefins and methane in the catalytic pyrolysis of C_(5) hydrocarbons were analyzed,and the effects of reaction conditions and zeolite types were inves-tigated.Results showed that light olefins were mainly formed by breaking the C_(2)-C_(3) bond in the middle position,while methane was formed by breaking the C_(1)-C_(2) bond at the end.Meanwhile,it was discovered that the hydrogen transfer reaction could be reduced by about 90%by selecting MTT zeolite with 1D topology and FER zeolite with 2D topology under high weight hourly space velocity(WHSV)and high temperature operations,thus leading to the improvement of the light olefins selectivity for the catalytic pyrolysis of n-pentane and 1-pentene to 55.12% and 74.60%,respectively.Moreover,the fraction ratio of terminal C_(1)-C_(2) bond cleavage was reduced,which would reduce the selectivity of methane to 6.63%and 1.83%.Therefore,zeolite with low hydrogen transfer activity and catalytic pyrolysis process with high WHsV will be conducive to maximize light olefins and to decrease methane.

Correlation Models for Light Olefin Yields from Catalytic Pyrolysis of Petroleum Residue

Correlation models for light olefin yields from residue catalytic pyrolysis are studied. Experiments are carried out in a confined fluidized bed reactor for Daqing (China) atmospheric residue catalytic pyrolysis over LCM-5 pyrolyzing catalyst. The influences of reaction temperature, residence time and the weight ratios of catalyst-to-oil and steam-to-oil on light olefin yields are researched. Correlation models for light olefin yields are established, and the model parameters obtained, with the least square method. Results for error analysis and the F-statistical test show that the correlation models have high calculation precision.

The role and potential of attapulgite in catalytic pyrolysis of refinery waste activated sludge

Pyrolysis is a promising technology for the treatment of refinery waste activated sludge(rWAS).In this study,attapulgite as a natural clay was used to enhance the pyrolysis of rWAS.The yields,characteristics of pyrolytic products,pyrolytic kinetics and mechanisms were investigated.The attapulgite improved the conversion of rWAS into non-condensable gases and pyrolytic liquids.The bio-oil quality improved and the biochar yield reduced.The average activation energy of Stage Ⅰ(230-400℃)and Stage Ⅱ(400-500℃)decreased by 36.5%and 49.7%,respectively,compared to rWAS alone.Al_(2)O_(3)and Fe_(2)O_(3)in attapulgite enhanced the dealkylation reaction and cracking of C-C bonds.The content of the gasoline(<C_(13))fraction of bio-oil doubled relative to rWAS alone.Attapulgite promoted the deoxygenation,dehydroxylation and dehydrogenation reactions of O-containing compounds,and the content of CO and CO_(2) in non-condensable gases increased.Addition of attapulgite(rWAS:attapulgite ratio of 1:1)decreased the O mobility from 14.6%to 12.8%relative to rWAS alone.Also,the content of saturates in bio-oil increased from 38.5 wt%to 47.2 wt%and the lower heating value(LHV)increased from 6.8 kcal/kg to 8.4 kcal/kg.The heavy metals originally in rWAS were fixed into the pyrolytic residue and the environmental risks are low.This study demonstrates the role and potential of attapulgite in catalytic pyrolysis of rWAS with an added advantage of increased cost-effectiveness.

Catalytic Pyrolysis of Soybean Oil with CaO/Bio-Char Based Catalyst to Produce High Quality Biofuel

In this paper,CaO/bio-char was synthesized by directly co-pyrolysis of Ca(OH)_(2) and rice straw,and used as catalyst to catalytic pyrolysis of soybean oil to produce high quality biofuel.In this co-pyrolysis process,CaO particles has been successfully embedded on the bio-char surface.During the catalytic pyrolysis process,CaO/biochar showed a good catalytic performance on the deoxygenation of soybean oil.Pyrolysis temperature affected the pyrolysis reactions and pyrolytic products distributions dramatically,higher pyrolysis temperature lead to seriously cracking reactions,lower bio-oil yield and higher gases yield,and lower pyrolysis temperature lead to higher bio-oil yield with higher oxygenated compounds content and lower hydrocarbons contents,the suitable pyrolysis temperature was around 650℃.Under the optimal conditions(650℃ with WHSV at 6.4 h^(−1) and carrier gas flow rate at 100 ml/min),the selectivity(%)of hydrocarbons in the bio-oil was more than 90%.CaO/bio-char catalyst still shows good catalytic deoxygenation activity after 4 cycles.1 g of CaO/bio-char catalyst can catalyze pyrolysis of 32 g of soybean oil to produce high-quality liquid fuel.Bio-char based catalyst has been proved to be a promising catalyst for catalytic conversion of triglyceride-based lipids into high quality liquid biofuel.

Techno-Economic Evaluation of Thermal and Catalytic Pyrolysis Plants for the Conversion of Heterogeneous Waste Plastics to Liquid Fuels in Nigeria

Techno-economic potentials of thermal and catalytic pyrolysis plants for the conversion of waste plastics to liquid fuels have been widely studied, but it is not obvious which of the two plants is more profitable, as the existing studies used different assumptions and cost bases in their analyses, thereby making it difficult to compare the economic potentials of the two plants. In this study, industrial-scale thermal and catalytic waste plastics pyrolysis plants were designed and economically analyzed using ASPEN PLUS. Amorphous silica-alumina was considered the optimum catalyst, with 3:1 feed to catalyst ratio. Based on 20,000 tons/year of feed and 20% interest rate, the catalytic plant, having a net present value (NPV) of &#83582208 million, was found to be economically less attractive than the thermal plant, having the NPV of &#83582426.4 million. On the contrary, sensitivity analyses of the two plants at a feed rate of 50,000 tons/year gave rise to a slightly higher NPV for the catalytic plant (&#83589861 million) than the thermal plant having NPV of &#83589838 million, thereby making the former more economically attractive for processing large amounts of waste plastics into liquid fuels. Consequently, as the catalytic plant showed a better scale economy and would produce higher quality liquid fuels than the thermal plant, it is recommended for commercialization in Nigeria.

Importance of oxygen-containing functionalities and pore structures of biochar in catalyzing pyrolysis of homologous poplar

Biochar and bio-oil are produced simultaneously in one pyrolysis process,and they inevitably contact and may interact,influencing the composition of bio-oil and modifying the structure of biochar.In this sense,biochar is an inherent catalyst for pyrolysis.In this study,in order to investigate the influence of functionalities and pore structures of biochar on its capability for catalyzing the conversion of homologous volatiles in bio-oil,three char catalysts(600C,800C,and 800AC)produced via pyrolysis of poplar wood at 600 or 800℃or activated at 800℃,were used for catalyzing pyrolysis of homologous poplar wood at 600℃,respectively.The results indicated that the 600C catalyst was more active than 800C and 800AC for catalyzing cracking of volatiles to form more gas(yield increase by 40.2%)and aromatization of volatiles to form more light or heavy phenolics,due to its abundant oxygen-containing functionalities acting as active sites.The developed pores of the 800AC showed no such catalytic effect but could trap some volatiles and allow their further conversion via sufficient aromatization.Nevertheless,the interaction with the volatiles consumed oxygen on 600C(decrease by 50%),enhancing the aromatic degree and increasing thermal stability.The dominance of deposition of carbonaceous material of a very aromatic nature over 800C and 800AC resulted in net weight gain and blocked micropores but formed additional macropores.The in situ diffuse reflectance infrared Fourier transform spectroscopy characterization of the catalytic pyrolysis indicated superior activity of 600C for removal of -OH,while conversion of the intermediates bearing C=O was enhanced over all the char catalysts.

Production of aryl oxygen-containing compounds by catalytic pyrolysis of bagasse lignin over LaTi0.2Fe0.8O3 prepared by different methods

To realize the resource and high-value utilization,a new approach,named bagasse lignin(BL) used to produce aryl oxygen-containing compounds by catalytic pyrolysis over perovskite,was proposed,LaTi0.2Fe0.8O3(LTF) samples prepared by the sol-gel method(SG) and the solid-state reaction method(SS)were characterized.The catalytic action on BL pyrolysis was performed by the test of TG-DTG and the evaluation of the fixed bed micro-reactor,the components and contents of the products were determined.The results show that LTF samples have cubic perovskite phase,LTF prepared by SG(LTF-SG) is porous with larger specific surface area than LTF prepared by SS(LTF-SS).During the pyrolysis of BL,the addition of LTF lowers the pyrolysis temperature and the activation energy,the contents of CO2 and CO in gaseous products reduce by 4.6%-8.0% and 30.7%-34.3%,respectively,the total content of aryl oxygencontaining compounds(including phenolics,guaiacols,syringols and phenylates) in liquid products increases from 62 wt% to more than 72 wt%,and LTF-SG shows better catalytic performance.LTF samples have nice phase and catalytic stabilities for BL pyrolysis after five successive redox cycles.

Catalytic pyrolysis of Pubescens to phenols over Ni/C catalyst

The pyrolysis of Pubescens over Ni/C catalyst was studied at 350°C in H2 flow.The presence of Ni/C catalyst efficiently improved the degradation of raw materials,and produced bio-oil with high content of phenols but low contents of acetic acid,furfural and water.In the reaction,Ni/C catalyst plays the role of catalytic decomposition and catalytic hydrogenation.The existence of the carbon carrier favors the formation of active Ni in small sizes with more defects,which results in high catalytic activity of Ni in biomass decomposition and selective production of phenols.

Preparation of bio-oil by catalytic pyrolysis of corn stalks using red mud

Red mud is a solid waste residue with alkaline nature(pH>12)-originating from the Bayer process in the production of alumina,which was probed in catalytic pyrolysis to determine its feasibility as a solid catalyst for bio-oil formulation.The red mud was characterized using X-ray fluorescence,XRD(X-ray diffraction),TG-DTG(thermogravimetry-derivative thermogravimetry),BET(surface area and pore size analyzer)measuring and testing techniques.Experiments of non-catalytic and catalytic pyrolysis of 40-60 mesh size corn stalk powder were channelled for bio-oil production in a fixed bed reactor.It was ascertained that adding different proportions of red mud had minute influence on bio-oil production rate and product distribution.The study signaled that liquid yield from the catalytic pyrolysis was lower than that from non-catalytic pyrolysis.Through a series of bio-oil characterization,it was encountered that the most obviously change in the bio-oil from catalytic pyrolysis was significant acidity reduction(pH>4).Meanwhile,the content of ketones and phenols was enhanced.Hence,the co-processing of agricultural waste and by-products alumina industry may offer an economical and environmentally friendly way of catalytic pyrolysis with abbreviating the red mud environmental effects.

Directional preparation of naphthalene oil-rich tar from Beisu low-rank coal by low-temperature catalytic pyrolysis

Low-rank coal(LRC)can be converted to high value-added naphthalene and its alkylated derivatives through low-temperature catalytic pyrolysis.In this paper,the catalytic pyrolysis of Beisu LRC in a fixed-bed at low temperature was investigated.And the catalytic effects of HZSM-5,low-temperature carbocoal(LtC),and LtC-HZSM-5 on the content and yield of naphthalene oil were examined.The results showed that the generation of naphthalene oil in low-temperature LRC pyrolysis(LT-LP)process could be improved when LtC(prepared at 550℃)or HZSM-5 was individually used as a catalyst.Compared with sole pyrolysis of raw LRC,the addition of the LtC-HZSM-5 catalyst increased the content of naphthalene oil from 11.19 wt.%to 31.49 wt%.And the yield of naphthalene oil was increased from 1.07 wt%to 5.31 wt%.The reactions of micromolecular hydrogen-containing radicals(⋅MHCR)were optimized by LtC.⋅MHCR could be captured in relatively low-temperature region(200-400℃)and released at high temperature by LtC.The generation of phenolics was inhibited by HZSM-5.As a result,the naphthalene oil-rich tar was obtained through low-temperature LtC-HZSM-5 catalytic pyrolysis of Beisu LRC.

Production of phenolic compounds in catalytic pyrolysis of bagasse lignin in the presence of Ca_(0.5)Pr_(0.5)FeO_(3)

Herein,sodium dodecylbenzene sulfonate(SDBS)was used as a template to control the synthesis of Ca_(0.5)Pr_(0.5)FeO_(3).Its microstructure,composition,and morphology were detected via X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM).The properties of catalyzing bagasse lignin(BL)pyrolysis were determined by thermogravimetric analysis(TG)test and evaluation of a fixed bed alumina microreactor.The results show that the sample Ca_(0.5)Pr_(0.5)FeO_(3)regulated by SDBS has a cubic crystal phase,and the addition of SDBS does not cause phase transition.Moreover,when the SDBS concentration is 0.10 mol/L,the particle size is 200-500 nm and the specific surface area is 11.26 m^(2)/g.The yields of gas,liquid,and solid products in the BL catalytic pyrolysis are 39.58 wt%,26.76 wt%and 32.36 wt%,respectively.The contents of CO_(2)and CO decrease from 54.07%and 4.98%to 45.29%and 3.23%,respectively.The liquid products are mainly guaiacol,syringol,and phenol,and the total selectivity of phenols is 83.67%,accompanied by a small amount of non-aromatic oxygen-containing compounds(five-membered ring(furan)or ester).Compared with the BL pyrolysis and Ca_(0.5)Pr_(0.5)FeO_(3)catalytic pyrolysis products,the selectivity of guaiacol compounds increases by43.26%,while those of syringol compounds and phenylketones decrease by 30.08%and 3.39%,respectively.The selectivity of 2,6-dimethoxyphenol is 28.37%.After five catalytic pyrolysis-regeneration cycles,the characteristic peaks of the catalyst do not change significantly and the particles are uniform,suggesting that the catalyst has good crystal phase stability and regeneration stability.

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha.Herein,for a better catalyst design and operation parameters optimization,the reaction pathways and equilibrium yields for the catalytic pyrolysis of C_(5-8)n/iso/cyclo-paraffins were analyzed thermodynamically.The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways,respectively.However,the formation of light paraffin severely limits the maximum selectivity toward light olefins.The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins.The results are thus useful as a direction for future catalyst improvements,facilitating superior reaction pathways to enhance light olefins.In addition,the equilibrium yield of light olefins increased with increasing the chain length,and the introduction of cyclo-paraffin inhibits the formation of light olefins.High temperatures and low pressures favor the formation of ethylene,and moderate temperatures and low pressures favor the formation of propylene.n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90%and 55.77%,respectively.This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C_(5-8)n/iso/cyclo-paraffins from a thermodynamic point of view.

Hierarchical ZSM-11 with intergrowth structures:Synthesis,characterization and catalytic properties

Hierarchical ZSM-11 microspheres with intercrystalline mesoporous properties and rod-like crystals intergrowth morphology have been synthesized using a spot of tetrabutylammonium as a single template.XRD,FTIR,SEM,TEM and N2 adsorption analysis revealed that each individual particle was composed of nanosized rod crystals inserting each other and the intercrystalline voids existing among rods gave a significant mesopore size distribution.Steam treatment result demonstrated the excellent hydrothermal stability of samples.Various crystallization modes including constant temperature crystallization (one-stage crystallization) and two-stage temperature-varying crystallization with different 1st stage durations were investigated.The results suggested that the crystallization modes were mainly responsible for the adjustable particle size and textural properties of samples while the small amount of tetrabutylammonium bromide was mainly used to direct the formation of both ZSM-11 framework and its intergrowth morphology.Furthermore,the performance of optimal ZSM-11 as an active component for the catalytic pyrolysis of heavy oil was also investigated.Compared with the commercial pyrolysis catalyst,the hierarchical ZSM-11 catalyst exhibited a high selectivity to desired products(LPG+gasoline+diesel),as well as a much lower dry gas and coke yield,plus a high selectivity and yield of light olefins(C=3 C=4)and very poor selectivity to benzene.Therefore,fully open micropore-mesopore connectivity would make such hierarchically porous ZSM-11 zeolites very attractive for applications in clean petrochemical catalysis field.

Diameter-Controlled Growth of Carbon Nanotubes Through Pyrolysis of Acetylene Using Rare Earth Alloy as Catalyst in Hydrogen

High-purity carbon nanotubes(CNTs)were synthesized in hydrogen ambience by CVD method by (using) rare earth alloy MlM_(5-1.35)(CoAlMn)_(1.35) as catalyst, acetylene as carbon source. The influence of hydrogen flow rate on the diameter, shape, purity, graphitization degree and output of carbon nanotubes was systematically studied by scanning selectronic microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD)and Raman technique. The results indicate that the size of MlM alloy particles changed from μm order into nm order during the process of hydrogen reduction. While no introducing hydrogen in the reaction of acetylene and catalyst, CNTs can also be synthesized on the catalyst. The CNTs are short and thick with average diameter of about 97.8 nm, and the wall of CNTs is also thick and rough. With increasing of hydrogen flow rate, the diameter of CNTs first decrease and then increase, while the output, purity, and graphitization degree first increase and then decrease. The optimized conditions are: CNTs reach its narrowest size with diameter of 49.1 nm when hydrogen flow rate is 50 ml·min^(-1). The purity, graphitization degree, and output of CNTs reach highest and largest when hydrogren flow rate is 75 ml·min^(-1). It has the most uniform tube size of 97.38 nm when hydrogen flow rate is 100 (ml·min^(-1).)

Production of Bio-Oil from Pyrolysis of Olive Biomass with/without Catalyst

In this study olive biomass was pyrolysis in a 400 cm3 stainless steel reactor. It was externally heated by an electrical furnace in which the temperature is measured by a thermocouple inserted into the bed. The effect of the catalyst ratio to the biomass (5%, 10%, 15%, 20%, 30% and 40%) on the pyrolysis yield was investigated and compared with the uncatalyzed pyrolysis yield product. The bio-oil products yield from the pyrolysis process was found to increase as the catalyst ratio increased. The bio-oil yield from the olive oil-cake, which was 36.1% without the catalyst, reached the maximum value of 39.3% on using activated catalyst at 10% by weight. The gas products yield was found to increase upon using catalyst compared to the non-catalytic pyrolysis. The reduction in the bio-oil yield product was accompanied with a significant reduction in the oxygen content. The pyrolysis oil was examined using chromatographic analysis techniques. The chemical characterization showed that the bio-oil obtained from olive oil cake might be potentially valuable as a fuel and chemical feedstock.

Kinetics and Products Distribution Study on the Catalytic Effect of Zn/HZSM-5 over Pyrolysis of Chlorella through TG-FTIR and Py-GC/MS

In this study,both the pyrolysis and catalytic pyrolysis behaviour of chlorella were investigated using thermogravimetric analysis combined with Fourier Transform Infrared spectrum(TG-FTIR)and Py-GC/MS.The results of TG indicated the pyrolysis of chlorella was divided into three stages,and the Coats-Redfern kinetic model was used for the analysis and validation of the obtained thermal data.The regression coefficients indicated that the pyrolysis of chlorella was close to second-order reaction.The activation energy of pyrolysis of chlorella and catalytic pyrolysis of chlorella+HZSM-5,chlorella+Zn/HZSM-5 was 61.645,59.080 and 56.808 kJ·mol^(−1),respectively.Combined with the data of FTIR,we found that the addition of the HZSM-5 effectively reduced the activation energy required by pyrolysis;the addition of the Zn/HZSM-5 could not only reduce the activation energy,but also reduce the yield of oxygen-containing compounds,increase the emissions of CO_(2),and facilitate the production of high value-added hydrocarbon products.These results were also verified by Py-GC/MS that the addition of Zn/HZSM-5 could reduce the formation of ketones and aldehydes and increase the production of nitrogen-containing compounds.Thus,through the catalytic pyrolysis of chlorella,the utilization range of chlorella can be expanded,and better bio-oil can be obtained,which will play a crucial role in the selection of available energy in the future.

Energetic,bio-oil,biochar,and ash performances of co-pyrolysis-gasification of textile dyeing sludge and Chinese medicine residues in response to K_(2)CO_(3),atmosphere type,blend ratio,and temperature

Hazardous waste stream needs to be managed so as not to exceed stock-and rate-limited properties of its recipient ecosystems.The co-pyrolysis of Chinese medicine residue(CMR)and textile dyeing sludge(TDS)and its bio-oil,biochar,and ash quality and quantity were characterized as a function of the immersion of K_(2)CO_(3),atmosphere type,blend ratio,and temperature.Compared to the mono-pyrolysis of TDS,its co-pyrolysis performance with CMR(the comprehensive performance index(CPI))significantly improved by 33.9%in the N_(2)atmosphere and 33.2%in the CO_(2)atmosphere.The impregnation catalyzed the co-pyrolysis at 370℃,reduced its activation energy by 77.3 kJ/mol in the N_(2)atmosphere and 134.6 kJ/mol in the CO_(2)atmosphere,and enriched the degree of coke gasification by 44.25%in the CO_(2)atmosphere.The impregnation increased the decomposition rate of the co-pyrolysis by weakening the bond energy of fatty side chains and bridge bonds,its catalytic and secondary products,and its bio-oil yield by 66.19%.Its bio-oils mainly contained olefins,aromatic structural substances,and alcohols.The immersion of K_(2)CO_(3)improved the aromaticity of the copyrolytic biochars and reduced the contact between K and Si which made it convenient for Mg to react with SiO_(2)to form magnesium-silicate.The co-pyrolytic biochar surfaces mainly included-OH,-CH_(2),C=C,and Si-O-Si.The main phases in the co-pyrolytic ash included Ca_(5)(PO_(4))_(3)(OH),Al_(2)O_(3),and magnesium-silicate.

PREPARATION OF MULTI-WALLED CARBON NANOTUBES USING NiO CATALYST SYNTHESIZED BY HYDROTHERMAL METHOD

The Ni(OH)2/SiO2 binary colloid was prepared using Ni(NO3)2.6H2O and (C2H5O)4SiO4 as starting materials and was used to form NiO/SiO2. composite powder by hydrothermal method and desiccant method in open air respectively. Multi-walled carbon nanotubes (MWCNTs) were synthesized respectively by chemical vapor deposition using the NiO/SiO2 catalyst prepared by different methods. The phase and morphology of the catalysts and the morphology, output yield and purity of MWCNTs were compared by XRD, TEM and SEM. The results show that the catalyst powder prepared by hydrothermal method, compared with that by desiccant method, is smaller, better dispersion and has stronger catalytic activity. Pure MWCNTs with smaller tube diameter and narrow range could be obtained at a high yield using that NiO/SiO2 powder prepared by hydrothermal method as catalyst.

Catalytic fast pyrolysis of Kraft lignin with HZSM-5 zeolite for producing aromatic hydrocarbons

Catalytic fast pyrolysis （CFP） of Kraft lignins with HZSM-5 zeolite for producing aromatics was investigated using analytical pyrolysis methods. Two Kraft lignins were fast pyrolyzed in the absence and presence of HZSM-5 in a Curie-point pyrolyzer. Without the catalyst, fast pyrolysis of lignin predominantly produced phenols and guaiacols that were derived from the subunits of lignin. However, the presence of HZSM-5 changed the product distribution dramatically. As the SiO2/ A1203 ratio of HZSM-5 decreased from 200 to 25 and the catalyst-to-lignin ratio increased from 1 to 20, the lignin- derived oxygenates progressively decreased to trace and the aromatics increased substantially. The aromatic yield increased considerably as the pyrolysis temperature increased from 500~C to 650~C, but then decreased with yet further increase of pyrolysis temperature. Under optimal reaction conditions, the aromatic yields were 2.0 wt.% and 5.2 wt.% for the two lignins that had effective hydrogen indexes of 0.08 and 0.35.