间接模板剂法合成介孔SAPO-11分子筛及其加氢异构化性能

采用水热合成法,将未焙烧的介孔材料SBA-15作为硅源合成介孔SAPO-11分子筛。利用X射线衍射、N2吸附-脱附等温曲线,BET物理吸附,NH3-TPD以及扫描电子显微镜等对分子筛的形貌和孔结构性质进行表征。将正十二烷作为原料,考察负载量为0.5%的Pt/SAPO-11分子筛催化剂的加氢异构化反应催化性能。结果表明:以未焙烧的SBA-15作为硅源制备介孔SAPO-11分子筛,介孔比表面积为77.2 m2/g以及介孔孔容为0.261 m~3/g,有效降低孔道传质阻力,酸量显著增加,活性位增多,使长链烷烃加氢异构化的选择性达到65.21%。     

多级孔道5A分子筛的合成及其对正构烷烃的吸附性能研究

为了提高5A分子筛对正构烷烃吸附分离的速率,以二甲基十八烷基[3-(三甲氧基硅基)丙基]氯化铵(TPOAC)为软模板剂,采用水热合成方法合成出具有微孔和介孔结构的多级孔道5A分子筛。结果表明,合成的分子筛以0.5 nm左右的微孔为主,介孔孔道集中在7~13 nm。通过改变模板剂用量可以调控合成分子筛的介孔数量。合成的多级孔道5A分子筛在保持对正构烷烃具有较高平衡吸附量的同时,显著提高正构烷烃在分子筛内的扩散系数,从而提高吸附分离的速率。     

复合分子筛在烃类异构化反应中的应用研究进展

近年来研究者发现复合分子筛具有孔结构丰富、水热稳定性良好、表面性质可调控等优点,在烃类异构化反应中表现出比单一分子筛更高的反应活性和更好的异构体选择性。本文综述了丝光沸石分子筛（MOR）、Y型分子筛、β分子筛、ZSM系列分子筛、SAPO系列分子筛等两两复合的微孔-微孔复合分子筛和微孔分子筛与MCM-41分子筛、SBA-15分子筛等介孔分子筛复合的微孔-介孔复合分子筛在烷烃异构化、烯烃异构化等反应中的应用研究进展,并对用于烃类异构化复合分子筛的研究与发展方向进行了展望,指出复合分子筛用于真实石油馏分的异构化研究仍需更深入、系统地展开;采用绿色高效的合成方法合成复合分子筛以及探究通过复合分子筛的结构设计和酸性调控,如何进一步提高复合分子筛在烃类异构化反应中的活性和选择性是未来研究的重点。     

探针分子3-乙基-十一烷的合成

针对SAPO- 11的一维十元环直孔道结构,设计了具有特殊分子结构的长链烷烃3-乙基-十一烷.3-乙基-十一烷与目前常用的长直链探针分子相比,具有能卡在SAPO- 11分子筛孔口的特点,因此可以作为特殊的长链探针分子,结合直链探针分子,对SAPO-11负载催化剂在长链正构烷烃异构化反应中的孔口催化机理进行研究.3-乙基...     

小晶粒ZSM-22的可控合成及其催化长链正构生物烷烃制航空煤油性能

由生物脱氧油制生物航空煤油具有较大应用潜力和发展前景,为了提高生物航煤的收率,开发性能更好的加氢裂化/异构化催化剂是关键。本文采用水热合成法,在低温陈化、加入晶种、提高合成凝胶的碱度或加入有机碱条件下,合成了平均c轴尺寸在100~330nm的小晶粒ZSM-22分子筛,进行了XRD、SEM、N₂物理吸附、NH₃-TPD和吡啶红外表征,并以生物质油加氢脱氧得到的长链正构生物烷烃为原料,考察了不同晶粒尺寸 ZSM-22催化剂催化裂化和异构化制生物航空煤油的性能。结果表明,通过提高碱度合成的小晶粒H-ZSM-22 具有较强的酸中心,较多可及的强B酸中心数量,其长链正构烷烃转化率可达80%以上。在此基础上,制备的Pt/ZSM-22催化剂具有较高的Pt分散度,表现出很好的加氢裂化/异构化性能,其长链正构烷烃的转化率高达97.79%,生物航煤收率达50.25%,航煤产物异正比为7.55。     

正构烷烃在Pt/SAPO-11催化剂上加氢异构反应性能

采用SAPO-11分子筛制备Pt/SAPO-11双功能加氢异构催化剂,以n-C_8、n-C_(12)和n-C_(16)为模型化合物考察正构烷烃的加氢异构反应性能。结果表明,所制备的催化剂具有较好的异构化活性和选择性,其中单甲基支链异构产物收率和总异构产物收率分别可达60%和75%以上,是低凝柴油和高档润滑油基础油的理想组分。不同链长正构烷烃的异构化产物分布基本一致,但链长较长的正构烷烃更容易发生异构化反应和裂解反应,在保证相同转化率条件下长链烷烃裂解产物收率偏高且异构选择性降低。     

Pt/ZSM-35催化长链正构生物烷烃加氢裂化/异构化制航空煤油

以生物质油加氢脱氧得到的长链正构生物烷烃为原料，考察了H-MCM-49、H-ZSM-5、H-ZSM-22和 H-ZSM-35这4种不同分子筛催化剂的物化性质及其加氢裂化/异构化制生物航空煤油的性能。在此基础上，以H-ZSM-35分子筛为载体，制备并表征了一系列低负载量（0.1%、0.2%和0.3%）的Pt/ZSM-35双功能催化剂，以长链正构生物烷烃转化率、C₉~C₁₆产物选择性、生物航空煤油收率和异正比为指标，对其加氢裂化/异构化制生物航空煤油反应性能进行了评价，并对反应工艺条件进行优化。结果表明：H-ZSM-35的强酸中心强度高、酸量大，其结构中较小的孔口和较大的球型笼使其具有一定的容烃量和较好的择形性能，0.1%~0.3% Pt负载后， Pt/ZSM-35双功能催化剂表现出很好的加氢裂化/异构化活性和选择性。采用0.1% Pt/ZSM-35双功能催化剂在反应条件为320℃、1MPa、0.7h^-1、氢油比840∶1时，长链正构生物烷烃的转化率为84.3%，生物航空煤油收率达41.1%，产物异正比为1.34。81h长运转测试结果表明，该催化剂具有很好的稳定性。     

正构烷烃在Pt/SAPO-11催化剂上加氢异构反应性能

采用SAPO-11分子筛制备Pt/SAPO-11双功能加氢异构催化剂,以n-C₈、n-C₁₂和n-C₁₆为模型化合物考察正构烷烃的加氢异构反应性能。结果表明,所制备的催化剂具有较好的异构化活性和选择性,其中单甲基支链异构产物收率和总异构产物收率分别可达60%和75%以上,是低凝柴油和高档润滑油基础油的理想组分。不同链长正构烷烃的异构化产物分布基本一致,但链长较长的正构烷烃更容易发生异构化反应和裂解反应,在保证相同转化率条件下长链烷烃裂解产物收率偏高且异构选择性降低。     

分子筛催化剂的研究进展

综述了常用分子筛催化剂的研究现状及发展趋势,总结了烷烃异构化的反应特点,介绍了具有代表性的中孔分子筛类催化剂、硅磷铝分子筛类催化剂、杂多酸等催化剂的合成方法、条件及应用前景。着重介绍了各类催化剂的性能和最新研究状况,具体包括MCM-41、SAPO-11、沸石分子筛等,同时对目前面临研究问题进行概述。最后指出绿色、中低温合成烷烃异构化催化剂将是未来的研究热点。     

MCM-41介孔分子筛催化剂的制备及催化性能的研究

文章采用碱性水热晶化法制备MCM-41介孔分子筛为载体,用浸渍法将非贵金属Ni和12-硅钨杂多酸(HSi W)固载于分子筛上,制备得Ni-HSi W/MCM-41金属-酸双功能催化剂作为新型的长链烷烃异构化催化剂。研究了Ni-HSi W/MCM-41双功能催化剂在常压固定床反应器上,以正庚烷异构化反应为探针反应,催化剂在不同制备条件下的催化性能。结果表明催化剂在一定还原条件和反应条件下当Ni固载量为4 wt.%、HSi W固载量为30%,催化剂的焙烧温度为400℃时是最佳制备条件。     

Recent Advances and Future Aspects in the Selective Isomerization of High n-Alkanes

This article provides an overview of the advances that have been marked during the last decades in the field of hydroconversion of high n-alkanes (C₇⁺) with particular stress on the promising ways to meet the requirements for improved quality of motor fuels and oils. Particular attention is given to a catalyst formulation for selective conversion of high n-alkanes to branched hydrocarbons. The challenge for successfully solving this problem is to find an effective catalyst favoring the isomerization of n-alkanes without too much cracking. The regulation of active sites and adsorption properties, as well as the topology of support surfaces, allows a more predictive design of novel catalysts for selective conversion of high n-alkanes into their branched isomers.     

The effect of mass transfer on the catalytic combustion of benzene and methane over palladium catalysts supported on porous materials

Catalytic combustion of benzene and methane over palladium catalysts supported on FAU and MOR zeolites and MCM-41 and KIT-1 mesoporous materials were studied to illustrate the effect of pore size and shape of supports on their catalytic activities. The palladium catalysts supported on mesoporous materials showed high activity and a steep increase in the conversion of benzene with rising temperature. The low activity of palladium catalysts supported on FAU zeolite was ascribed to mass transfer limitation. However, conversion profiles of methane on palladium catalysts were similar, although their supports were different as zeolites and mesoporous materials. The catalytic behavior of palladium catalysts in the combustion of benzene and methane was explained by the diffusion properties of fuels in the pores of zeolites and mesoporous materials.     

Recent Advances and Future Aspects in the Selective Isomerization of High n‐Alkanes

This article provides an overview of the advances that have been marked during the last decades in the field of hydroconversion of high n‐alkanes (C₇ ⁺) with particular stress on the promising ways to meet the requirements for improved quality of motor fuels and oils. Particular attention is given to a catalyst formulation for selective conversion of high n‐alkanes to branched hydrocarbons. The challenge for successfully solving this problem is to find an effective catalyst favoring the isomerization of n‐alkanes without too much cracking. The regulation of active sites and adsorption properties, as well as the topology of support surfaces, allows a more predictive design of novel catalysts for selective conversion of high n‐alkanes into their branched isomers.     

On the way to improve cetane number in diesel fuels: Ring opening of decalin over Ir-modified embedded mesoporous materials

Embedded materials prepared from MCM-41 together with BE or TON were synthesized, characterized and tested in the ring opening of decalin in a temperature range of 523–623 K. The characterization results revealed that both microporous and mesoporous phases were present in the catalyst. Ir-modification did not change the phase purity, affecting, however, the acidity due to metal-support interactions. The parameters studied in ring opening of decalin were support structure, presence of Ir and temperature. The detailed analysis of 2D/3D isomers and ring opening products showed that the main ring opening products contained ethyl side chain. The Ir-modified embedded mesoporous catalysts were active and relatively selective in the ring opening of decalin, giving 35% selectivity to the ring opening products at 98% conversion at 573 K and 6 MPa.     

磺酸化碳材料负载Ru催化剂催化纤维素水解/加氢反应

采用纤维素衍生碳、活性炭和介孔碳材料CMK-3为不同碳源前驱体,在不同磺酸化条件下制备磺酸化碳材料负载Ru的双功能催化剂,并用FTIR光谱、XRD、元素分析、热重分析、N₂物理吸附 脱附进行了表征,考察了其对纤维素加氢反应的催化活性。结果表明：相比于纤维素衍生化碳,活性炭和介孔碳CMK-3为碳源经过磺酸化后制备的催化剂具有较强的结合-SO₃H的能力和较高的催化活性,对多元醇具有良好的选择性,170 ℃下反应10 h六元醇的收率可高达84.0%。在循环使用时,磺酸化活性炭负载Ru催化剂催化活性有所降低,但可以保持对多元醇的选择性;而磺酸化介孔碳负载Ru催化剂存在少量S流失,转化率基本不变,但产物的选择性有所降低。     

New effective catalysts based on mesoporous nanofibrous carbon for selective oxidation of hydrogen sulfide

The systems based on granular mesoporous nanofibrous carbonaceous (NFC) materials synthesized by decomposition of hydrocarbons over nickel-containing catalysts are promising catalysts for selective oxidation of hydrogen sulfide. Sample series of nanofibrous carbon with three main types of their fiber structures and different contents of metal catalysts inherited from the catalysts for their synthesis were studied in this reaction. The correlation between NFC structure and its activity and selectivity in hydrogen sulfide oxidation was determined. The metal inherited from the initial catalysts for the synthesis of NFC influences the activity and selectivity of the resulting carbon catalysts. A particular influence is observed in the case of the catalyst withdrawn from the synthesis reactor at the stage of stationary operation of the metal catalyst (low specific carbon yields per unit weight of the catalyst). The presence of the metal phase results in an increase in the carbon catalyst activity and in a decrease in the selectivity to sulfur. NFC samples with the highest activity and selectivity are nanotubes and those with graphite planes perpendicular to the axis of the fibers. Carbon nanotubes have high selectivity, while samples obtained on copper–nickel catalysts also possess high activity. The promising NFC catalysts provide high conversion and selectivity (almost independent of the molar oxygen/hydrogen sulfide ratio) when a large excess of oxygen is contained in the reaction mixture.     

Direct synthesis and catalytic performance of ultralarge pore GaSBA-15 mesoporous molecular sieves with high gallium content

Mesoporous GaSBA-15 molecular sieves with different n_Si/n_Ga ratios have been directly synthesized using Pluronic 123 triblock polymer as a structure-directing agent by pH-adjusting method. The mesoporous materials have been characterized using ICP-AES, XRD, N₂ adsorption, ⁷¹Ga-MAS NMR, SEM and TEM. ICP-AES studies show a high amount of gallium incorporation on the silica pore walls. The structural and textural properties of calcined GaSBA-15 are characterized by XRD and N₂ adsorption. ⁷¹Ga MAS NMR results demonstrate that a high amount of tetrahedral-gallium could be substituted for Si in the framework of SBA-15. TEM and FE-SEM images show the uniform pore diameter and rope-like hexagonal mesoporous structure of GaSBA-15. These GaSBA-15 materials have been used as catalysts for vapour-phase t-butylation of 1,2-dihydroxybenzene (DHB) for selective synthesis of 4-t-butylcatechol (4-TBC) under different reaction conditions. GaSBA-15(10) gave the highest 93.2% conversion of DHB and 95.7% selectivity of 4-TBC as compared with other GaSBA-15 catalysts.     

Ethylene polymerization catalyzed by metallocene supported on mesoporous materials

Summary  In this work, different mesoporous materials were employed for the preparation of supported metallocene catalysts to be evaluated in ethylene polymerization and their performance was related to the chemistry of the materials surface used as support. The supports employed were MCM-41, SBA-15 and mesoporous TiO₂. The performance of the prepared catalysts was compared with the homogeneous catalyst precursor system. Those mesoporous materials, as well as the prepared metallocene catalysts, were analyzed by infrared absorption spectrometry (FTIR). Polymers were also characterized by FTIR, for the determination of the number-average molecular weight, and by differential scanning calorimetry (DSC) to determine thermal characteristics of the produced polyethylene. Among the studied metallocene supported catalysts, the one based on the mesoporous support SBA-15 achieved the highest activities, almost as high as that observed for the homogeneous system.     

The reversible skeletal isomerization between n-butenes and iso-butene over solid acid catalysts

The reversibility of skeletal isomerization between n-butenes and iso-butene has been studied over various solid acid catalysts including ferrierite and ZSM-5 zeolites, mesoporous materials and amorphous alumina in order to identify the cause for their different selectivities for skeletal isomerization. A remarkable selectivity for the reverse skeletal isomerization of iso-butene to n-butenes is found from ferrierite, fluorinated alumina with low fluorine loading and the KIT-1 mesoporous material with low aluminium content; which also demonstrate high selectivity for forward skeletal isomerization. Catalysts that are not selective for forward isomerization exhibit poor selectivity for reverse isomerization. The preference for multimolecular oligomerization due to high concentrations of activated reactants in the pores of nonselective catalysts reduces their selectivity for skeletal isomerization. Thus, the suppression of oligomerization over the selective catalyst makes the cracking of oligomers impossible and increases selectivity. This is achieved by a sparse distribution of activated reactants caused by specific pore structures or low concentrations of strong acid sites. The reversibility of skeletal isomerization and the adsorbed state of butenes are discussed in relation to the monomolecular reaction path.