丙烷芳构化催化剂活性组分浸渍方法优化

根据现有丙烷芳构化催化剂的特性,考察等体积浸渍、真空等体积浸渍、微波等体积浸渍3种不同浸渍方法对镓改性HZSM-5催化剂性能的影响,并结合多种技术表征,分析改性后催化剂内部性能变化情况。研究发现,浸渍方法对催化剂表面镓的分散度具有明显的影响,其中真空等体积浸渍具有更好的效果,使活性组分Ga分散更均匀,更有效地降低了分子筛的B酸位、增加了L酸位,进而抑制了丙烷的裂解,增强了催化剂的脱氢、芳构化能力,并且延长了催化剂的寿命。在反应温度为525℃,丙烷质量空速(WHSV)为1h-1的条件下,取样时间为丙烷通入后1.3h,丙烷转化率达到93.8%,液相芳烃收率达到57.2%,BTX(苯、甲苯和二甲苯)收率达到48.6%。     

Zn/NaHZSM-5沸石在C5～C8链烷烃芳构化反应中的催化性能

采用氨气程序升温脱附（NH₃-TPD）、紫外-可见光谱和小型固定床反应器，重点研究了碱金属钠离子和过渡金属锌离子改性对纳米H-ZSM-5沸石表面酸性及其催化C₅～C₈链烷烃芳构化反应性能的影响。结果表明，用碱金属钠离子改性能够有效地消除沸石表面的强酸中心，适当降低催化剂表面酸量，从而减少甲烷、乙烷和丙烷等低值副产物的生成，优化芳构化反应产物分布。适宜的Zn²⁺负载量为3%（质量分数），过高的Zn²⁺负载量会使产物中干气生成量增大，不利于芳烃收率的提高。C₅～C₈链烷烃芳构化的适宜反应温度为530℃。     

La改性ZSM-5分子筛及其在催化裂解反应中的应用

采用高温水热法和等体积浸渍法将La离子负载于ZSM-5分子筛上得到了改性ZSM-5分子筛材料。水热法La改性样品改变了ZSM-5的晶胞尺寸,提升了其强酸、弱酸及总酸量。浸渍法改性样品也提高了其酸量但是对晶胞参数没有影响。将改性样品应用于正己烷催化裂解反应中,两种方法均得到了较高的双烯收率,其中水热法改性样品在空速为6 h^-1时乙烯收率和丙烯收率分别为23.39%和25.17%,这与原样相同空速下的乙烯丙烯收率（乙烯为21.19%,丙烯为21.04%）相比分别提升了约2%和4%,略高于浸渍法改性样品。在长周期反应寿命方面也有了显著提高,在空速为4 h^-1时,水热法改性样品（2000 min）和浸渍法改性样品（1600 min）均显著优于原样（800 min）。这些结果表明采用水热法La改性可以更好地提升ZSM-5分子筛在正己烷催化裂解反应中的性能。     

无溶剂合成多级孔ZSM-5分子筛及丙烷芳构化反应性能研究

以无溶剂合成方法,利用生物质多糖海藻酸钠制备了具有多级孔道结构的ZSM-5分子筛。采用XRD、SEM、TEM、FT-IR和N2吸附-脱附等多种表征技术对合成分子筛进行了表征,探究了海藻酸钠的添加量对分子筛形貌、孔结构、比表面积等物化性质的影响。结果表明,通过添加海藻酸钠制备的ZSM-5分子筛是具有丰富的多级孔结构,其添加量显著影响分子筛的形貌和孔结构,进而影响其在丙烷芳构化反应中的稳定性和芳构化选择性。该分子筛经Zn改性后用于丙烷芳构化反应,显示出良好的催化性能,其中样品Zn/ZSM-5-SA-16.7的丙烷转化率最初达87.2%,反应进行24 h后,丙烷转化率仍能达到50%以上,并且保持了较高的芳烃选择性（接近60%）。引入介孔结构有利于提高微孔分子筛内有机大分子的扩散速率和催化剂活性位的可接近性,降低副反应的发生,进而提高催化剂的选择性和反应稳定性。     

不同类型氧化铝对FCC轻汽油芳构化性能影响

针对第六阶段汽油国家（国Ⅵ）标准大幅度降烯烃同时保辛烷值的生产需要，本文通过改变氧化铝基质类型，制备了系列催化裂化（FCC）轻汽油芳构化催化剂，并对催化剂酸性质和织构性质进行调变。采用X射线衍射（XRD）、N₂吸附脱附、扫描电子显微镜（SEM）、红外光谱（IR）和吡啶红外光谱（Py-IR）等手段对催化剂的物理性质进行表征，并以工业FCC轻汽油为原料对催化剂芳构化性能进行评价。实验结果表明，不同类型氧化铝的引入未对ZSM-5分子筛晶型产生影响，但可以显著调变ZSM-5分子筛的表面酸性，增加L酸中心数量。具有均一和相对较小比表面积和孔容的氧化铝材料更有利于轻汽油芳构化性能，轻汽油产品中，烯烃大幅下降（体积分数减少18.18%），异构烷烃（体积分数提高10.51%）和芳烃（体积分数提高2.75%）增幅较为明显，辛烷值损失（-5.1）较小并且可控。     

催化裂化汽油在多元沸石基催化剂上加氢改质研究

采用浸渍法分别制备了以丝光沸石（HM）、Hβ和HZSM-5及其组合为载体的沸石基Ni-Mo-P催化剂,考察了载体组成对催化裂化汽油加氢改质反应性能的影响。结果表明,由适宜比例的三者组合得到的沸石基Ni-Mo-P催化剂具有良好的加氢异构化、脱硫、芳构化活性及稳定性,可在催化裂化汽油脱硫降烯烃的同时保证产品的辛烷值不降低。考察了工艺条件对三元沸石基Ni-Mo-P催化剂反应性能的影响。在温度300 ℃、氢油体积比350、液相体积空速2.5 h-1和反应压力1.5 MPa反应条件下,催化裂化汽油异构烷烃收率、芳烃收率、脱硫率及液相收率分别达41.9%、31.7%、51.0%和98.3% 。     

ZSM-5/γ-Al2O3质量比对FCC轻汽油异构化/芳构化性能影响

通过调变ZSM-5分子筛与γ-Al₂O₃质量比,采用等体积浸渍法制备系列FCC轻汽油异构化/芳构化催化剂。本文采用X射线衍射（XRD）、N₂吸附脱附、扫描电子显微镜（SEM）、氨气程序升温脱附（NH₃-TPD）、红外光谱（IR）和吡啶红外光谱（Py-IR）等手段对其进行表征,并以乌鲁木齐石化醚后C₅掺杂液化石油气（LPG）为原料对催化剂异构化/芳构化性能进行评价。实验结果表明,ZSM-5分子筛与γ-Al₂O₃质量比的调变可以改变催化剂的酸性质及孔结构性质。在反应温度380℃、反应压力1.0MPa、反应空速1.0h^-1、氢/油体积比100、LPG进量4.4g/h的条件下,ZnLa/ZSM-5/γ-Al₂O₃-1异构化/芳构化产物与反应原料相比,烯烃体积分数降低27.49%、异构烷烃体积分数增加15.87%、芳烃体积分数增加3.97%,辛烷值损失3.38个单位,产品收率高达89.90%,实现了异构化/芳构化大幅降烯烃保辛烷值的目标。     

正庚烷芳构化催化剂的研究

以正庚烷为原料,金属锌改性的氢型ZSM-5分子筛和γ-Al_20_3为催化剂,采用常压连续微型反应装置,以正庚烷芳构化反应所收集的芳构化产物选择性、收率和原料转化率为标准,考察了锌组分负载量、焙烧温度和焙烧时间对催化剂芳构化性能的影响。实验结果表明:该催化剂在3%的锌配比,550℃下焙烧3h所得的芳构化产物中苯、甲苯、二甲苯的含量达到90.65%,证明此催化剂是一种较为高效的芳构化催化剂。     

ZSM-5催化剂上FCC汽油加氢脱硫及芳构化性能的研究

采用四丙基氢氧化铵与氢氧化钠混合碱溶液对ZSM-5分子筛进行改性,运用X射线衍射、扫描电镜、N2物理吸附和NH3程序升温脱附等手段对样品进行表征。结果表明,改性后HZSM-5分子筛的介孔数量增多,比表面积、孔体积增大,强酸位酸量增多。在催化裂化汽油加氢脱硫及芳构化反应中,ZSM-5分子筛催化剂性能优异,呈现出良好的脱硫性能及烯烃芳构化活性。在压力为3 MPa,温度为300℃,氢油体积比为300∶1,空速为1.5 h-1的条件下,FCC汽油脱硫率达到94.2%,芳烃产率为20.7%     

Zn/NaHZSM-5沸石在C_5～C_8链烷烃芳构化反应中的催化性能

采用氨气程序升温脱附(NH_3-TPD)、紫外-可见光谱和小型固定床反应器,重点研究了碱金属钠离子和过渡金属锌离子改性对纳米H-ZSM-5沸石表面酸性及其催化C_5～C_8链烷烃芳构化反应性能的影响。结果表明,用碱金属钠离子改性能够有效地消除沸石表面的强酸中心,适当降低催化剂表面酸量,从而减少甲烷、乙烷和丙烷等低值副产物的生成,优化芳构化反应产物分布。适宜的Zn~(2+)负载量为3%(质量分数),过高的Zn~(2+)负载量会使产物中干气生成量增大,不利于芳烃收率的提高。C_5～C_8链烷烃芳构化的适宜反应温度为530℃。     

Effects of Pre-Treatment of a Silica-Supported Gallium Oxide Catalyst with H2 on Its Catalytic Performance for Dehydrogenation of Propane

The pre-treatment of a silica-supported gallium oxide catalyst with H₂ at 823 K increased the yield of aromatics and the selectivity to aromatics in the dehydrogenation of propane over the catalyst at 823 K. Gallium oxide in the catalyst was partially reduced with H₂ at 823 K. NH₃ desorption and DRIFTS studies on the gallium oxide catalyst suggest that the dehydrogenation of propane over a silica-supported gallium oxide catalyst would proceed in the following way: (1) the dehydrogenation of propane to produce propene would occur on Ga sites including Ga^δ+–H sites and (2) the aromatization of propene to aromatics on Ga–O–H acid sites.     

氧化镧助剂对镍/二氧化硅催化剂结构和加氢性能的影响

采用等体积浸渍法制备了La₂O₃改性的Ni/SiO₂催化剂,考察了La₂O₃的引入方法对Ni/SiO₂催化剂催化间二硝基苯加氢制间苯二胺反应性能的影响,并采用XRD、TPR和XPS等表征技术对催化剂的物化性质进行了研究.结果表明,La₂O₃的添加顺序对Ni/SiO₂催化剂的物化性质和加氢性能影响非常明显.当镧以先于镍浸渍方式引入时,将大大削弱载体与镍物种之间的相互作用,镍晶粒度变小,分散度增加,催化剂的活性显著提高,间二硝基苯转化率和间苯二胺收率分别达到97.1%和93.5%.在以镍和镧共浸方式制备的催化剂中,La₂O₃的存在也使Ni/SiO₂催化剂的反应性能有所改善,但效果没有镧先于镍浸渍方式突出.当以先浸镍后浸镧的方式加入助剂时,催化剂中的镍晶粒增大,分散性变差,催化剂的活性大幅度下降.     

Preparation, evaluation and characterization of copper catalysts for ethanol fuelled diesel engines

Copper-based monolithic honeycomb catalysts for ethanol fuelled diesel engines have been prepared and evaluated. The washcoat consisted either of alumina or titania. Two different methods to apply the active material were used; incipient wetness impregnation and deposition precipitation. The catalysts have been evaluated in a laboratory reactor and have been characterised using SEM, XRPD, TEM, TPR, XPS, BET surface area and pore-size distribution measurements. Both the choice of washcoat material as well as the preparation method is of importance. Titania as washcoat gave a better performing catalyst than alumina in this case. Deposition precipitation gave a better catalyst than incipient wetness impregnation when alumina was used as washcoat, as well as at low temperatures for titania catalysts.     

Cracking of n-heptane over Brønsted acid sites and Lewis acid Ga sites in ZSM-5 zeolite

A series of gallium-containing ZSM-5 zeolites prepared by wet impregnation, ion-exchange and chemical vapor deposition (CVD) methods are compared in the cracking of n-heptane. Impregnation results in the dispersion of some of the gallium oxide clusters into the zeolite pore network as charge-compensating Ga species after calcination. Reduction of impregnated Ga/HZSM-5 catalysts leads to complete transformation of the oxidic Ga precursors to charge-compensating Ga⁺ and GaH²⁺ species. A small amount of divalent GaH²⁺ species can be stabilized; however, with increasing Ga/Al ratio monovalent cations dominate. While a model Ga/HZSM-5 catalyst prepared by CVD of Ga(CH₃)₃ containing mainly charge-compensating Ga cations displays high selectivity to dehydrogenated products (olefins, toluene and coke), catalysts with a lower Ga/Al ratio display improved activity with a product mixture resulting from contributions of Ga sites (dehydrogenation, aromatization, olefin cracking) and of Brønsted acid sites (protolytic cracking, olefin cracking). The synergy between Ga dehydrogenation sites and Brønsted acid sites is proposed to improve the dehydrogenation rate: the high acidity of the zeolitic proton facilitates hydrogen recombination and concomitant removal of product olefin from the Ga active sites. Ion-exchanged Ga/HZSM-5 catalyst which combines a difficult to reduce gallium oxide phase and high Brønsted acidity has the highest activity with relatively weak coke formation.     

Tungstophosphoric and Molybdophosphoric Acids Supported on Zirconia as Esterification Catalysts

The preparation and characterization of supported acid catalysts, based on tungstophosphoric (TPA) or molybdophosphoric (MPA) acids using ZrO₂ as support, are presented. ZrO₂ was prepared from zirconium oxychloride aqueous solutions by adding ammonium hydroxide solution. Two different techniques were used to obtain the catalysts, equilibrium adsorption and incipient wetness impregnation. The catalyst characterization allowed us to determine the species present on the carrier surface and their acidic properties. The catalytic activity for esterification of acetic acid with isoamyl alcohol of the zirconia-supported TPA catalysts was greater than that corresponding to those based on MPA. Moreover, in the preparative conditions used, the incipient wetness impregnation led to heteropolyacids supported on ZrO₂ with better catalytic performance.     

磷改性对氯化Ni-W/SiO2/γ-Al2O3降烯烃催化剂性能的影响

采用氯化处理后的硅铝载体，通过等体积浸渍法分别制备了磷改性前后的两种Ni-W/硅铝催化剂。利用FR/IR-560和Digisorb-2400物理吸附仪对两种催化剂的酸度、比表面积、孔径和孔容等进行了表征，同时利用荧光指示剂吸附法对磷改性前后催化剂降烯烃的性能进行了考察。结果表明，磷改性使催化剂的B酸中心数量增加了0.02 mmol·g^－1，而B酸中心的增加有利于双分子的氢转移反应,避免反应过程中催化剂表面的积炭。在催化剂活性方面，磷改性使催化裂化汽油中的烯烃含量降低了3.06个百分点，同时提高了产品油的液体收率；从产品分布看，含磷催化剂的液体产品中异构烷烃和芳烃比例均有所提高，说明磷的加入增加了异构化和芳构化的反应活性。     

Methane Aromatization over Cobalt and Gallium -Impregnated HZSM-5 Catalysts

The influence of the catalyst acidity, the ratio of cobalt in the catalyst on the conversion of methane and the stability were evaluated using a fixed-bed microreactor at atmospheric pressure and at a flow rate of 1500 mL/g h (GHSV 600 h^?1). The reaction was conducted at 973 K and 1023 K over gallium and cobalt -impregnated HZSM-5 catalysts. The 2%Ga–2% Co/HZSM-5 catalyst exhibited remarkable stability with no significant deactivation for 100 h on stream, and yielded a maximum conversion of methane to benzene equal to 9.9%. These catalysts were thoroughly characterized using XRD, N₂ adsorption measurements, TPD of NH₃ and FT-IR. The acidity changes severely affected aromatization, and resulted in drastic modifications in product distribution. From this work, we found that only a small fraction of tetrahedral framework aluminum, which corresponds to the Bronsted acid sites, is sufficient to accomplish the aromatization of the intermediates in methane aromatization reaction, while the superfluous strong Bronsted acid sites, which can be decreased by adding Ga and Co, are shown to be related with the aromatic carbonaceous deposits on the catalysts. After adding Ga and Co the strength of Lewis acid sites of the catalyst increased. But the total amount of the acidity on the catalyst decreased.     

V205／Si02催化氧化乙二醛制备乙醛酸的研究

以SiO2为载体,采用等体积浸渍法合成V205／SiO2催化剂,用XRD对催化剂进行了表征,并考察了不同条件对催化氧化乙二醛制备乙醛酸的影响。结果表明,当负载量为1％、焙烧温度为550℃、反应温度为55℃、催化剂用量为0．20g时,催化效果最好,乙二醛的转化率可达12．02％,乙醛酸的得率为9．01％。     

Co/Al_2O_3催化剂制备及其合成重质烃的反应性能

以不同孔道结构Al_2O_3作载体,甲醇、乙醇和柠檬酸作分散剂,通过等体积浸渍法制备系列Co/Al_2O_3费托合成催化剂。采用XRD、TG-DSC和H2-TPR等考察制备方法对催化剂结构的影响,并在固定床反应器中对催化剂进行性能评价。结果表明,采用具有适宜孔道结构Al_2O_3作载体才能获得综合性能较好的催化剂,3种分散剂的加入,促进了钴物种在载体上的分散,增强了钴与载体间的相互作用,改善了催化剂费托合成反应活性,显著提高了重质烃时空收率。