Hydrogen Production by Low-temperature Steam Reforming of Bio-oil over Ni/HZSM-5 Catalyst

We investigated high catalytic activity of Ni/HZSM-5 catalysts synthesized by the impregnation method, which was successfully applied for low-temperature steam reforming of bio-oil. The influences of the catalyst composition, reforming temperature and the molar ratio of steam to carbon fed on the stream reforming process of bio-oil over the Ni/HZSM-5 catalysts were investigated in the reforming reactor. The promoting effects of current passing through the catalyst on the bio-oil reforming were also studied using the electrochemical catalytic reforming approach. By comparing Ni/HZSM-5 with commonly used Ni/Al2O3 catalysts, the Ni2O/ZSM catalyst with Ni-loading content of about 20% on the HZSM-5 support showed the highest catalytic activity. Even at 450 ℃, the hydrogen yield of about 90% with a near complete conversion of bio-oil was obtained using the Ni2O/ZSM catalyst. It was found that the performance of the bio-oil reforming was remarkably enhanced by the HZSM-5 supporter and the current through the catalyst. The features of the Ni/HZSM-5 catalysts were also investigated via X-ray diffraction, inductively coupled plasma and atomic emission spectroscopy, hydrogen temperature-programmed reduction, and Brunauer-Emmett-Teller methods.

Ni改性HZSM-5催化剂对混合C_(4)中异丁烯齐聚的影响

近年来,乙醇汽油全面推广导致甲基叔丁基醚(MTBE)的应用受限,作为其原料之一的异丁烯需要另寻出路。异丁烯主要来源于催化裂化和蒸气裂解所产生的混合C_(4)馏分,其通过选择性二聚反应可以生产高辛烷值的汽油添加剂。以Ni为助剂对HZSM-5进行改性,考察不同Ni负载量对催化性能的影响,并对一系列催化剂进行相关表征。结果表明,当Ni负载质量分数为0.25%时,综合效果最好,C_(8)^(=)收率为45.4%。表征结果表明,HZSM-5经Ni改性后,强酸位点的Lewis酸(L酸)和Bronsted酸(B酸)比值增加,对提高产物C_(8)^(=)选择性具有重要作用,该L酸中心可能来源于Ni物种与HZSM-5中的铝相互作用所生成的NiAl_(2)O_(4)。

Ethanol steam reforming over Ni/ZSM-5 nanosheet for hydrogen production

Compared to reforming reactions using hydrocarbons,ethanol steam reforming(ESR)is a sustainable alternative for hydrogen(H_(2))production since ethanol can be produced sustainably using biomass.This work explores the catalyst design strategies for preparing the Ni supported on ZSM-5 zeolite catalysts to promote ESR.Specifically,two-dimensional ZSM-5 nanosheet and conventional ZSM-5 crystal were used as the catalyst carriers and two synthesis strategies,i.e.,in situ encapsulation and wet impregnation method,were employed to prepare the catalysts.Based on the comparative characterization of the catalysts and comparative catalytic assessments,it was found that the combination of the in situ encapsulation synthesis and the ZSM-5 nanosheet carrier was the effective strategy to develop catalysts for promoting H_(2) production via ESR due to the improved mass transfer(through the 2-D structure of ZSM-5 nanosheet)and formation of confined small Ni nanoparticles(resulted via the in situ encapsulation synthesis).In addition,the resulting ZSM-5 nanosheet supported Ni catalyst also showed high Ni dispersion and high accessibility to Ni sites by the reactants,being able to improve the activity and stability of catalysts and suppress metal sintering and coking during ESR at high reaction temperatures.Thus,the Ni supported on ZSM-5 nanosheet catalyst prepared by encapsulation showed the stable performance with~88% ethanol conversion and~65% H_(2) yield achieved during a 48-h longevity test at 550-C.

Study on the in situ desulfurization and viscosity reduction of heavy oil over MoO_(3)–ZrO_(2)/HZSM-5 catalyst

Heavy oil is characterized by high viscosity.High viscosity makes it challenging to recover and transport.HZSM-5,MoO_(3)/HZSM-5,ZrO_(2)/HZSM-5 and MoO_(3)–ZrO_(2)/HZSM-5 catalysts were developed to promote in situ desulfurization and viscosity reduction of heavy oil.The physical and chemical properties of catalysts were characterized by XPS,XRD,TEM,NH3-TPD,etc.The effects of temperature,catalyst type and addition amount on viscosity and composition of heavy oil were evaluated.The results showed that the presence of MoO_(3)–ZrO_(2)/HZSM-5 nanoparticles during aquathermolysis could improve the oil quality by reducing the heavy fractions.It reduced viscosity by 82.56%after the reaction at 280℃ and catalyst addition of 1 wt%.The contents of resins and asphaltic in the oil samples were 5.69%lower than that in the crude oil.Sulfur content decreased from 1.45%to 1.03%.The concentration of H2S produced by the reaction was 2225 ppm.The contents of sulfur-containing functional groups sulfoxide and sulfone sulfur in the oil samples decreased by 19.92%after the catalytic reaction.The content of stable thiophene sulfur increased by 5.71%.This study provided a basis for understanding the mechanism of heavy oil desulfurization and viscosity reduction.

Preparation and Catalytic Application of Novel Water Tolerant Solid Acid Catalysts of Zirconium Sulfate/HZSM-5

Esterification of acrylic acid（AA） to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorption, TGA-DTA, XPS, and ammonia adsorption FTIR. The effects of Si/Al ratio, zirconium sulfate（ZS） loading on HZSM-5 and calcination temperature on the esterification were investigated. When 20% （mass fraction） ZS is loaded on HZSM-5, the conversion of AA reaches 100%. XRD analysis indicates that ZS is highly dispersed on HZSM-5 because no crystalline structure assigned to ZS is found. Catalytic activity and hydrophobicity of ZS supported on HZSM-5 are higher compared with those of parent ZS or HZSM-5. Results show that this kind of novel catalysts is an efficient water tolerant solid acid catalyst for esterification reactions.

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.

Ni-P/HZSM-5催化木质素降解制备酚类化学品

采用Ni-P复合改性HZSM-5催化剂催化木质素降解制备高附加值的单酚类化学品,探讨了催化剂种类、金属负载量、反应温度、反应时间以及溶剂种类对木质素催化降解制备酚类化合物的影响。同时采用X射线衍射仪(XRD)、比表面积和孔径分析仪(BET)、化学吸附仪(NH3-TPD)、热重分析仪(TG)以及气相色谱质谱联用仪(GC/MS)对催化剂以及液相产物进行分析表征,同时探讨其催化失活以及再生机制。结果表明:Ni、P高度分散在HZSM-5催化剂的表面,Ni的添加有效地弱化了C-C键,致使β-O-4和α-O-4发生断裂,有效地提高了木质素加氢解聚的活性,减少了焦炭的生成,但催化剂的再生水热稳定性较差,重复使用性较低。当采用甲醇为供氢试剂,在反应温度为220℃,氢气压力为2MPa,反应时间为8h,催化剂负载量为10%,NaOH为共催化剂时,其木质素的转化率为98.6%,酚类化合物的含量达到74.97%。产物以苯酚、愈创木酚和紫丁香酚为主,低温促进了紫丁香酚的产生。

Ni/HZSM-5的结构及催化木糖醇水相加氢合成液体烷烃的性能研究

采用浸渍法制备了Ni/HZSM-5双功能催化剂,采用BET、XRD、NH3-TPD、H2-TPR、FTIR和TG等方法表征了催化剂比表面、孔结构、酸性、还原能力及骨架结构等信息,研究了其催化木糖醇水相加氢合成液体烷烃的性能及催化剂失活的原因。结果表明,在优化的金属中心/酸中心的协同作用下,木糖醇可通过水相加氢高选择性地合成C5-C6烷烃;过高的金属中心或酸中心均会导致C-C键断裂形成轻质烷烃,以2%Ni/HZSM-5催化剂上木糖醇水相加氢活性最高,木糖醇C转化率为94%液体烷烃总收率可达90%,这与其具有较大的比表面积、合适的孔径分布、较多的金属活性中心、适中的酸量和强酸量有关。催化剂6次重复使用后活性明显降低,其骨架部分脱铝和表面积碳是其失活的主要原因。

Ni-Fe/HZSM-5水蒸汽催化重整间甲酚制氢研究

采用共沉淀法制备Ni/HZSM-5、Ni-Fe/HZSM-5、Fe/HZSM-5催化剂,以XRD、BET、SEM为测试方法对其进行表征。在固定床反应器上,以间甲酚为生物油模型物进行水蒸汽催化重整制氢实验,考察了催化剂、反应温度、反应时间、水碳比对水蒸汽催化重整间甲酚制氢的影响。实验结果表明,反应温度650℃,反应时间120 min,水碳比8,使用Ni-Fe/HZSM-5催化剂时氢气产率达到最大,为54%。

Ni/HZSM-5上裂解汽油选择加氢裂化的研究

在连续流动固定床装置上,探讨了非贵金属Ni/HZSM-5催化剂对裂解汽油选择加氢裂化反应的特征,考察了镍含量、温度、压力、空速及氢烃体积比等参数的影响。随镍含量的增加,裂解汽油中C6+非芳烃转化率先增加后减小,镍含量为2.1%左右较为适宜。工艺条件中温度和压力的影响较大,空速次之,氢烃体积比最小。在380℃、3.0MPa、质量空速1.245h-1、氢烃体积比1000的条件下,以镍含量为2.1%的Ni/HZSM-5为催化剂,65h内裂解汽油中C6+非芳烃组分转化率保持在95%以上,而芳烃转化率仅有13%;加氢裂化产物中,C2+正构烷烃达80.96%,其中丙烷60.71%,而甲烷和异构烷烃较少。这表明非贵金属Ni/HZSM-5催化剂可高选择性地裂化C6+非芳烃,适用于裂解汽油加氢裂化制备芳烃联产低碳烷烃。

Co/Ni/ZSM-5催化改质热解煤气与煤焦油及其机理

以过量浸渍法制备不同Ni、Co比例改性的ZSM-5分子筛为催化剂,通过XRD、SEM-EDS、BET、NH_(3)-TPD对催化剂进行表征。研究不同配比的Ni/Co/ZSM-5催化剂、热解温度、催化剂添加量对神府煤热解煤气与煤焦油组分变化的影响。结果表明,经Ni3Co5Z催化剂催化后的热解煤气总体积分数较原煤提高11.69个百分点,其中H_(2)体积分数和CH4体积分数分别提高了4.25个百分点、5.37个百分点;650℃为最佳热解温度,H_(2)体积分数和CH4体积分数分别提高了6.77个百分点、0.50个百分点,而催化剂的加入量对煤气体积分数影响较小。当催化剂为Co3Ni5Z、催化剂添加量为0.3 g、热解温度为600℃时,煤焦油中芳香烃与酚类的面积分数较原煤分别提高了5.91个百分点、3.35个百分点。Ni/Co/ZSM-5催化剂的酸量与催化性能关系密切,一定程度的酸量能促进煤的热解,提高煤气的高价值气体组分产量,改善煤热解油品的品质。

Ni/HZSM-5催化热解玉米秸秆制取生物油的研究

在固定床中考察Ni/HZSM-5对生物质催化热解的影响,采用浸渍法制备Ni负载量不同的Ni/HZSM-5分子筛催化剂,通过粒度分析、SEM、XRD和BET表征催化剂,在不同催化剂条件下热解玉米秸秆制取生物油,对生物油的理化特性和液相产物的化学组成进行分析.结果表明,Ni在HZSM-5表面负载均匀,Ni改性未影响HZSM-5的晶体结构,改性HZSM-5的比表面积随着Ni负载量的增加而减小.与不加入催化剂相比,在HZSM-5作用下得到的生物油得率降低,同时,酸类、醛类、呋喃类等含氧化合物的含量降低,酚类的含量增加;在Ni/HZSM-5作用下,与在HZSM-5作用下相比,所得生物油的得率上升,含水率下降,酮类含量明显降低,酚类含量进一步提高,说明Ni改性HZSM-5分子筛对生物质热解产物中的酮类、酚类含量具有明显的调控作用.

双金属Ni-Co/HZSM-5催化剂上甲烷二氧化碳重整反应

采用等体积浸渍法制备一系列双金属Ni-Co/HZSM-5催化剂,考察反应温度和Ni与Co质量比对甲烷二氧化碳催化重整性能的影响。采用BET和H2-TPR表征催化剂的孔结构和还原性能,结果表明,负载的活性组分均匀分散在HZSM-5载体孔道内。Ni与Co之间存在协同作用,促进了Ni-Co/HZSM-5催化剂的还原性能。单金属Co催化剂几乎对甲烷没有转化活性,双金属Ni-Co催化剂催化活性明显提高,Ni与Co质量比6∶4时,催化剂甲烷二氧化碳重整反应的催化活性和稳定性优于单金属Ni催化剂。

焙烧温度对Ni/HZSM-5催化剂在甲烷二氧化碳重整反应中的影响

采用等体积浸渍法制备了负载量为10 wt%的Ni/HZSM-5催化剂,考察了不同焙烧温度对于甲烷二氧化碳重整反应的影响.利用BET、H2-TPR、NH3-TPD和XRD等技术对催化剂进行了表征.结果表明,500℃焙烧的催化剂具有较大的比表面积、较小的镍晶粒尺寸及较强的中强酸中心,该催化剂应用于甲烷二氧化碳重整反应具有较好的催化活性与稳定性.

Effects of ZrO_2 on the Performance of CuO-ZnO-Al_2O_3/HZSM-5 Catalyst for Dimethyl Ether Synthesis from CO_2 Hydrogenation

A series of composite catalysts were prepared by the wet mixing method, and the mass ratio of CuO-ZnO-Al2O3-ZrO2 component to HZSM-5 zeolite （molar ratio of SiO2 to Al2O3 being 25） was 2：1. The CuO-ZnO-Al2O3-ZrO2 （CuO/ZnO/Al2O3=3/6/1 by weight） component was prepared by a modified ＇two-step＇ co-precipitation method. The effects of ZrO2 on the performance of CuO-ZnO-Al2O3/HZSMo5 catalyst for dimethyl ether synthesis from CO2 hydrogenation were investigated. It was found that ZrO2 improved the properties of CuO-ZnO-Al2O3/HZSM-5 as a structural promoter.

Effects of Calcination Temperature on the Acidity and Catalytic Performances of HZSM-5 Zeolite Catalysts for the Catalytic Cracking of n-Butane

The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature （excluding 800 ℃）. The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature. The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5 zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.

Low-temperature activation of methane over rare earth metals promoted Zn/HZSM-5 zeolite catalysts in the presence of ethylene

At low temperature of 723 K, methane can be easily activated in the presence of ethylene in the feed, and converted to higher hydrocarbons （C2-C4） and aromatics （C6-C10）, through its reaction over rare metals modified Zn/HZSM-5 zeolite catalysts without undesirable carbon oxides formation. Methane can get 37.3% conversion over the above catalysts under low temperature, and the catalysts show a longer lifetime than usual metal supported HZSM-5 zeolite catalysts without adding any rare earth metals. The effects of methane activation over various rare earth metal promoted Zn/HZSM-5 catalysts on the products and influences of several reaction conditions such as temperature, catalyst lifetime and molar ratio of CH4/C2H4 have been discussed.

Study on attrition of spherical-shaped Mo/HZSM-5 catalyst for methane dehydro-aromatization in a gas–solid fluidized bed

As a potential methane efficient conversion process,non-oxidative aromatization of methane in fluidized bed requires a catalyst with good attrition resistance,especially in the states of high temperature,longtime rapid movement and chemical reaction.Existing evaluation methods for attrition resistance,such as ASTM D5757 and Jet Cup test,are targeted for fresh catalysts at ambient temperature,which cannot well reflect the real process.In this study,spherical-shaped Mo/HZSM-5 catalyst prepared by dipping and spray drying was placed in a self-made apparatus for attrition testing,in which the catalyst attrition under different system temperatures,running time and process factors was investigated with percent mass loss(PML),particle size-mass distribution(PSMD)and scanning electron microscope(SEM).Carbon deposition on the catalyst before and after activation,aromatization and regeneration was analyzed by thermogravimetry(TG),and the attrited catalysts were evaluated for methane dehydro-aromatization(MDA).The results show that the surface abrasion and body breakage of catalyst particles occur continuously,with the increase of system temperature and running time,and make the PML rise gradually.The process factors of activation,aromatization and regeneration can cause the catalyst attrition and carbon deposits,which broaden the PSMD in varying degrees,and the carbon-substances on catalysts greatly improve their attrition resistance at high temperature.Catalyst attrition has a certain influence on its catalytic performance,and the main reasons point to particle breakage and fine powder escape.

Effective synthesis of 5-amino-1-pentanol by reductive amination of biomass-derived 2-hydroxytetrahydropyran over supported Ni catalysts

A highly efficient and green process was developed for the synthesis of useful 5-amino-1-pentanol(5-AP)from biomass-derived dihydropyran by coupling the in situ generation of 5-hydroxypentanal(5-HP,via the ring-opening tautomerization of 2-hydroxytetrahydropyran(2-HTHP))and its reductive amination over supported Ni catalysts.The catalytic performances of the supported Ni catalysts on different oxides including SiO2,TiO2,ZrO2,γ-Al2 O3,and MgO as well as several commercial hydrogenation catalysts were investigated.The Ni/ZrO2 catalyst presented the highest 5-AP yield.The characterization results of the oxide-supported Ni catalysts showed that the Ni/ZrO2 catalyst possessed high reducibility and a high surface acid density,which lead to the enhanced activity and selectivity of the catalyst.The effect of reaction parameters on the catalytic performance of the Ni/ZrO2 catalyst was studied,and a high 5-AP yield of 90.8%was achieved in the reductive amination of 2-HTHP aqueous solution under mild conditions of 80℃and 2 MPa H2.The stability of the Ni/ZrO2 catalyst was studied using a continuous flow reactor,and only a slight decrease in the 5-AP yield was observed after a 90-h time-on-stream.Additionally,the reaction pathways for the reductive amination of 2-HTHP to synthesize 5-AP were proposed.

Coking behaviors and kinetics on HZSM-5/SAPO-34 catalysts for conversion of ethanol to propylene

The coke deposition on HZSM-5/SAPO-34 composite catalysts has been studied in the conversion of ethanol to propylene. The HZSM-5/SAPO-34 composite catalysts were synthesized by hydrothermal method（ZS-HS） and fully blending（ZS-MM）. The used catalysts were characterized by XRD, N;adsorption–desorption, TGA, TPO, elemental analysis, FTIR and XPS. The coking kinetics on both ZS-HS and ZS-MM has been investigated and their coking rate equations were obtained. The used ZS-MM catalyst had higher amount of coke and lower nC:nHthan the used ZS-HS. 90% of the coke was deposited in the micropores of ZS-HS, while almost 45% of the coke located in the micropores of ZS-MM. The coke deposited on ZS-HS catalyst was mainly graphite-like carbon species, whereas dehydrogenated coke species was the major on ZS-MM. The coking activation energy of ZS-MM was lower than that of ZS-HS, and the coking rate on ZS-MM was faster than on ZS-HS. In addition, the regeneration of ZS-MM catalyst showed that it had a good hydrothermal stability. The differences on coking behaviors on the two catalysts were due to their different acidic properties and textures.