2,6-二甲基苯酚催化胺化过程Pd/γ-Al2O3催化剂的失活和改性

 采用固定床反应器, 研究了Pd/γ-Al₂O₃催化剂在催化2,6-二甲基苯酚气相胺化合成2,6-二甲基苯胺反应中的稳定性,实验结果发现催化剂较易失活。采用BET、XPS、TG、TEM和IR手段对失活前后的Pd/γ-Al₂O₃催化剂进行了表征分析,并采用BaO对Pd/γ-Al₂O₃催化剂进行改性。结果表明,Pd/γ-Al₂O₃催化剂失活的原因主要是反应过程生成的胺类化合物吸附在γ-Al₂O₃载体的酸性中心产生积碳沉积所致。Pd/γ-Al₂O₃催化剂添加BaO,生成了铝钡尖晶石结构,有效地减少了Pd/γ-Al₂O₃的酸性,加快了反应中生成的2,6-二甲基环己胺和2,6-二甲基苯胺的脱附,有效地避免了催化剂因积炭失活,提高了催化剂的稳定性。     

ZrO2对Cu/Al2O3-ZrO2催化剂糠醛选择加氢活性的影响

 采用共沉淀法制备了Al₂O₃-ZrO₂复合氧化物,并以它为载体,浸渍法制备Cu 质量分数为24%的负载型Cu 基催化剂。运用X射线衍射(XRD)、H₂程序升温还原(H₂-TPR)、X射线能谱(XPS)对载体和催化剂进行表征,并考察了ZrO₂对Cu/Al₂O₃-ZrO₂催化剂糠醛选择加氢活性的影响。结果表明,载体中ZrO₂质量分数20%的Cu/Al₂O₃-ZrO₂催化剂对糠醛的选择加氢活性最高。与Cu/Al₂O₃催化剂相比,添加ZrO₂可以提高Cu/Al₂O₃-ZrO₂催化剂加氢活性,并有效提高较高反应温度下的糠醇选择性。     

硫酸铝法制备的ZrO2-Al2O3的孔结构和表面性质

 在NaAlO₂-Al₂(SO₄)₃法制备拟薄水铝石成胶过程中加入氧氯化锆, 得到ZrO₂-Al₂O₃样品。采用XRD、BET、SEM、Py-IR、NH₃-TPD方法对ZrO₂-Al₂O₃样品进行了表征。结果表明,ZrO₂质量分数小于5.6%时, ZrO₂-Al₂O₃样品的晶相为γ-Al₂O₃,当ZrO₂质量分数大于5.6%时,出现了t-ZrO₂的晶相;随着ZrO₂含量的增加_,样品的比表面积逐渐减小;ZrO₂质量分数从0增至6.6%,孔容从1.12cm³/g到1.17cm³/g,变化不大,随ZrO₂质量分数的增加,孔容开始下降;平均孔径随着ZrO₂质量分数的增加而逐渐增加,ZrO₂质量分数达到7.4%以后,随着ZrO₂质量分数的增加,孔径减小。ZrO₂的加入对γ-Al₂O₃的孔型结构没有影响。ZrO₂-Al₂O₃样品主要以L酸为主,有少量的B酸;随着ZrO₂含量的增加,总酸量略有增加,其中弱酸比例降低,而强酸和中强酸的比例提高。     

MoP/ZrO2-SiO2-Al2O3 催化剂的加氢脱硫活性

 采用溶胶-凝胶法制备了ZrO₂-SiO₂-Al₂O₃复合载体,并用共浸渍法制备负载型 MoP/ZrO₂-SiO₂-Al₂O₃催化剂,通过原位还原技术对催化剂进行还原处理后,在连续固定床反应器上,以柴油为原料考察了催化剂的加氢脱硫活性。结果表明,ZrO₂、SiO₂和Al₂O₃的摩尔比对催化剂的活性有很大的影响,当n _Zr/n _Si/n _Al为1/1/4时,催化剂的加氢脱硫效果最好;助剂 Ni 的加入对催化剂加氢脱硫活性的促进作用比较明显,助剂 Ni 的质量分数为6%时,催化剂表现出较高的催化活性,脱硫率达97.96%。     

复合SiO2-WO3催化剂的制备、表征及氧化脱除苯并噻吩性能

 采用溶胶-凝胶法制备了SiO₂-WO₃催化剂,并采用XRD、FT-IR、BET、TG-DTA等方法对催化剂进行表征。以苯并噻吩(BT)为模型化合物,H₂O₂为氧化剂,考察了催化剂的活性元素、制备方法、n(W)/n(Si)和焙烧温度对其催化氧化脱硫活性的影响。结果表明,W的引入降低了SiO₂的比表面积,SiO₂-WO₃催化剂中W的主物相为WO₃。在以W为活性组元,且n(W)/n(Si)为0.1时,500℃焙烧得到的SiO₂-0.1WO₃催化剂具有最好的催化脱硫活性。在模拟油20 mL、催化剂SiO₂-0.1WO₃用量0.04 g、n(H₂O₂)/n(S)为15.9、乙腈/模拟油体积比0.3、65℃反应60 min的条件下,苯并噻吩模拟油脱硫率可达99.3%。     

Co负载量对Co/γ-Al2O3催化剂F-T合成催化性能的影响

 制备了不同Co负载量的系列Co/γ-Al₂O₃催化剂,采用XRD、H₂-TPR和H₂-TPD等方法对其进行表征,并考察Co负载量对Co/γ-Al₂O₃催化剂催化F-T合成反应性能的影响。结果表明,随Co负载量的增加,Co/γ-Al₂O₃催化剂的催化活性先增加后降低,在Co负载量25％附近达到最大。Co/γ-Al₂O₃催化剂上Co₃O₄晶粒尺寸随Co负载量增加而逐渐增大,而催化剂的还原温度变化不大,催化剂的还原度和氢吸附量则随Co负载量增加先增大后降低。Co/γ-Al₂O₃催化剂的催化活性与其氢吸附量呈线性关系。     

Pd/Al2O3-TiO2催化剂的制备条件

 以含K₂O的Al₂O₃-TiO₂复合物为催化剂载体,考察了浸渍液pH值、浸渍液浓度、浸渍时间和焙烧温度对Pd/Al₂O₃-TiO₂催化剂颗粒的蛋壳厚度、Pd粒子粒径等的影响。采用BET、TEM等方法对所制备的催化剂进行了表征,选择较佳制备条件的Pd/Al₂O₃-TiO₂催化剂进行了C₄馏分选择加氢活性评价。结果表明,随着浸渍液pH值的减小,催化剂颗粒的蛋壳厚度增加;浸渍溶液的浓度越高,浸渍时间越长,越有利于金属在催化剂内层的分布;浸渍液的pH值并不会影响Pd/Al₂O₃-TiO₂催化剂Pd粒子最终的大小。催化剂焙烧温度越高,Pd粒子的平均直径越大,Pd的分散度越小。在反应温度40℃、压力1.5 MPa、体积空速8.0 h^-1、氢/炔摩尔比2.5的条件下,较佳制备条件的Pd/Al₂O₃-TiO₂催化剂催化C₄馏分加氢的炔烃转化率73%、丁二烯选择性85%、丁二烯损失率2.5%。     

超声波辐照浸渍法制备MnO2/γ-A12O3催化剂及其柴油催化氧化脱硫性能

 分别采用超声波辐照浸渍法和普通浸渍法制备了MnO₂/γ-Al₂O₃催化剂,运用电感耦合等离子体原子发射光谱（ICP-AES）和X射线衍射（XRD）对催化剂进行表征,在空气-异丁醛-MnO₂/γ-Al₂O₃体系中评价其对加氢柴油的氧化脱硫催化性能,并考察了反应温度、异丁醛用量、空气流量、溶剂类型和剂/油体积比对柴油氧化脱硫反应的影响。结果表明,超声波辐照浸渍法制备的MnO₂/γ-Al₂O₃催化剂对柴油氧化脱硫的催化性能明显优于普通浸渍法制备的催化剂。最适宜的催化柴油氧化脱硫反应的条件为：乙腈为溶剂、加氢柴油30 mL、温度35℃、异丁醛20 mmol、空气流量0.06 L/min、超声波辐照浸渍法制备的MnO₂/γ-Al₂O₃催化剂0.08 g、剂/油体积比1/6和催化氧化时间10 min。在此条件下可将柴油硫质量分数从542μg/g 降至31μg/g,柴油脱硫率和回收率分别为94.3%和93.3%。     

芘在不同加氢催化剂上反应性能的比较

 制备了CoMo/γ-Al₂O₃、NiMo/γ-Al₂O₃和NiW/γ-Al₂O₃ 3种不同金属配伍的加氢催化剂,在连续流动固定床微反装置上对其芘的加氢活性以及产物分布选择性进行评价,并考察在原料芘中添加吡啶对催化剂芘加氢性能的影响。结果表明,在相同反应条件下,NiMo/γ-Al₂O₃催化剂对芘的加氢活性较高,NiW/γ-Al₂O₃催化剂上的芘加氢转化率受吡啶的影响最小;相同芘转化率下,CoMo/γ-Al₂O₃催化剂上的芘中间环加氢产物选择性较高。     

钒作为加氢催化剂活性组分的研究Ⅰ.钒对 NiMo/Al2O3催化剂加氢性能的影响及表征

 以含V溶液浸渍法制备了一系列含V的 NiMo/Al₂O₃催化剂,考察了 V₂O₅质量分数对 NiMo/Al₂O₃催化剂加氢性能的影响,并对催化剂进行了 BET、SEM、IR-OH、紫外-可见漫反射光谱以及拉曼光谱表征。结果表明,含 V 的 NiMo/Al₂O₃催化剂加氢活性明显低于不含 V 的 NiMo/Al₂O₃催化剂;随着催化剂上 V₂O₅质量分数的增加,多聚体V的出现导致V-S相的加氢活性增加,催化剂加氢活性先迅速下降,再逐渐趋于平稳。     

ZSM-5/MCM-41介孔硅铝分子筛担载Pd和Pt制备加氢脱硫催化剂

将ZSM-5溶于偏硅酸钠水溶液,以十六烷基三甲基溴化铵作模板剂,用水热合成法自组装合成了具有较强酸性和不同SiO₂/Al₂O₃摩尔比(n(SiO₂)/n(Al₂O₃))的ZSM-5/MCM-41介孔硅铝分子筛（记为ZM(x),x=n(SiO₂)/n(Al₂O₃)）。以二苯并噻吩（DBT）质量分数为0.8%的十氢萘溶液为模型化合物,考察了Si-MCM-41和ZM(x)担载的Pd和Pt催化剂催化加氢脱硫（HDS）反应的活性。结果表明,担载Pt和Pd不会破坏ZM(x)的介孔结构;DBT在Pd催化剂上主要通过加氢路径脱硫,而在Pt催化剂上则直接脱硫和加氢2条反应路径并重;Si-MCM-41为载体的催化剂HDS活性较低并且失活较快,以ZM(x)为载体的Pd和Pt催化剂加氢活性、加氢脱硫活性、加氢裂化活性及稳定性都有显著提高;ZM(x)担载的Pt和Pd催化剂催化HDS反应的活性可能与其活性组分分散度以及载体的B酸和L酸比例（B/L）有关,具有较好的活性组分分散度和较高B/L比例的ZM(60)担载的Pd和Pt催化剂表现出最佳的加氢脱硫活性和稳定性。     

Fischer-Tropsch synthesis in a slurry reactor in the presence of nanosized cobalt catalysts synthesized in situ in a hydrocarbon medium

Fischer-Tropsch synthesis in a slurry reactor at a pressure of 20 atm and a temperature of 220–300°C in the presence of 100Co : 2Pd : (5–50)Al₂O₃ and 100Co : 2Pd : (20–50)ZrO₂ (parts by weight) catalysts in situ synthesized in a hydrocarbon medium has been studied. The catalysts were prepared by the decomposition of cobalt salts and promoters in melted petroleum paraffin P-2 at 300°C and in situ reduced with hydrogen. It has been found that the nanocatalyst containing 20 parts by weight of ZrO₂ exhibits the highest activity in the Fischer-Tropsch synthesis and provides the yield of liquid products of 70 g/m³ at a CO conversion of 80%.     

Pd和甲醛对Ag/C催化四氯化碳原位液相加氢脱氯性能的影响

采用100 mL反应釜,在N₂存在条件下,研究了Ag/C催化剂催化CCl₄液相原位加氢脱氯反应,考察了助催化剂Pd以及助剂甲醛溶液对CCl₄原位催化转化反应转化率和产物选择性的影响,并结合XRD、XPS表征技术分析了甲醛自身分解反应。结果表明,助催化剂Pd可以提高Ag/C催化剂的活性,以n(Pd)/n(Ag)为0.03的Pd-Ag/C催化剂的活性最高;但对产物CH₂Cl₂和CHCl₃的选择性没有影响,二者选择性之比仍维持在6/4。甲醛的加入明显提高Ag/C催化剂上CCl₄的转化率,同时也改变了产物分布;反应4 h,CCl₄转化率和CH₂Cl₂选择性均达到90%。甲醛主要起促进Ag/C催化剂表面Ag-Cl物种还原为Ag的作用。     

Pt(Pd)/Hβ催化剂催化正丁烷异构化反应特性的研究

用等体积浸渍法制备了Pt/Hβ和Pd/Hβ催化剂,采用高压连续微反装置在反应温度300～500℃、反应压力2.0 MPa、氢与烃的摩尔比3.0、液态空速1.25 h-1的条件下考察了催化剂催化正丁烷异构化反应的性能;采用N2吸附-脱附和SEM方法对催化剂进行了表征。实验结果表明,反应温度为350℃时,Pd/Hβ催化剂的性能优于Pt/Hβ催化剂;反应温度为400℃时,后者的性能优于前者。反应温度为400℃时,Pt/Hβ催化剂的适宜Pt负载量为0.6%(w),此时正丁烷转化率为65.6%,异丁烷选择性为55.6%;Pd/Hβ催化剂的适宜Pd负载量为0.3%(w),此时正丁烷转化率为64.6%,异丁烷选择性为44.8%。考察了助剂对Pt/Hβ和Pd/Hβ催化剂性能的影响,添加Cu,Sn,Zn的催化剂性能良好。     

Selective Hydrogenation of Maleic Anhydride to Succinic Anhydride Over Nickel-palladium Catalysts

Hydrogenation of maleic anhydride (MA) to succinic anhydride (SA) over Ni-Pd bimetallic catalysts prepared by impregnation method has been studied at different Pd contents, pressures and temperatures. Catalytic activity was greatly influenced by the Pd content, pressure and temperature. Use of 5wt%Ni-0.02wt%Pd/clay catalyst, the 100% conversion for MA and 100% selectivity for SA were obtained for MA hydrogenation at normal pressure. The catalysts were characterized by an array of techniques, including X-ray diffraction (XRD) and H₂ temperature-programmed reduction (TPR). XRD and TPR studies showed that nickel was present as Ni²⁺ species on the support, and that there was no elemental nickel (Ni⁰) and Ni₂O₃ in the unreduced samples. XRD and TPR also showed that Pd was as amorphous existence on the catalysts.     

金属助剂对Ni2P/SBA-15催化剂结构及二苯并噻吩加氢脱硫性能的影响

 以介孔分子筛SBA-15为载体,硝酸镍为镍源,磷酸氢二铵为磷源,采用共浸渍法制备了 P/Ni 摩尔比为0.8的 Ni₂P/SBA-15催化剂,然后添加 Li、Na、K、Mg、Ca、Sr 和 Ba 等金属助剂,制备了一系列不同金属助剂的M-Ni₂P/SBA-15(其中M为 Li、Na、K、Mg、Ca、Sr 和 Ba)催化剂。采用 XRD 对该系列催化剂的结构进行了表征,并以二苯并噻吩质量分数为1%的二苯并噻吩/十氢萘溶液为模型化合物,在微型固定床反应器上评价它们的加氢脱硫(HDS)性能。结果表明,M-Ni₂P/SBA-15催化剂的活性相为 Ni₂P。不同的金属助剂对催化剂性能的促进作用不同,其中碱土金属Ca能够明显地提高 Ni₂P/SBA-15催化剂的 HDS 活性,Ca 质量分数为3.5%的Ca-Ni₂P/SBA-15催化剂的 HDS 活性最好。在反应压力3.0 MPa、反应温度360℃的条件下,3.5%Ca-Ni₂P/SBA-15催化剂催化的二苯并噻吩 HDS 的转化率达到98.6%。不同金属助剂以不同方式影响加氢脱硫反应的机理。       

Isomerization of <Emphasis Type="Italic">n</Emphasis>-hexane over bifunctional Pt/SO<Subscript>4</Subscript>/ZrO<Subscript>2</Subscript> catalysts

The catalytic properties of model Pt/SiO₂ and Pt/Al₂O₃ catalysts and their physical mixtures with SO₄/ZrO2 in the reaction of n-hexane isomerization have been studied. Significant effects of the influence of the platinum state on the characteristics of isomerization on the catalysts and their physical mixtures with SO₄/ZrO₂ have been revealed. The observed changes in catalytic performance of the mixed catalysts have been explained from the position of a bifunctional mechanism with the participation of ionic platinum promoting the formation of hydride ions, which play an important role in the activation of transformations of intermediates in isomerization reactions.     

The Effect of Pd Precursors on the Catalytic Activity of a Pd/Al2O3 Catalyst for Cumene Hydroperoxide Hydrogenation

Abstract

Abstract Pd/Al₂O₃ catalysts were prepared by wet impregnation using K₂PdCl₄, (NH₄)₂PdCl₄, and Pd(NO₃)₂ as precursors. All catalysts were characterized by means of inductively coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction (TPR), X-ray diffraction (XRD), and CO chemisorption. The results obtained in the hydrogenation of cumene hydroperoxide (CHP) to α-cumyl alcohol (CA) showed that Pd/Al₂O₃ catalyst prepared from Pd(NO₃)₂ exhibited the highest turnover frequency (TOF) value and the greatest deactivation extent, whereas Pd/Al₂O₃ catalyst prepared from (NH₄)₂PdCl₄ displayed the lowest TOF value but the best stability.     

The effect of physical and chemical treatment on nano-zeolite characterization and their performance in dimethyl ether preparation

Catalytic dehydration of methanol to dimethyl ether (DME) was investigated using physically and chemically modified H-Mordenite and H-Beta zeolites as catalysts. Physical modification was carried out using ultrasonic wave’s energy, while chemical modification was performed through impregnation in aluminum nitrate followed by calcination. The produced solid catalysts were evaluated as selective catalysts for the dehydration of methanol to dimethyl ether at 100–250 °C performed at three different contact times. Chemical and structural characterizations of the solid catalysts were identified using XRD, FT-IR, TEM, SEM and NH₃-TPD. Ultrasonication physical mixing of solids proved as useful tool of preparation, producing fine reordered crystals of nanocomposite zeolites with novel morphology. The newly ordered crystals were distinguished by their frame work structure, acidic properties, crystal and particle sizes, unit cell volume, pore opening, and favorable catalytic activity of 100% selectivity to DME at 200 °C for all contact times studied. The effects of Al₂O₃ on the dispersion and interaction within the nano-zeolite crystals and hence on the catalytic dehydration of methanol were verified as the major influence toward utmost selectivity.