M/γ-Al2O3催化剂对煤油水重整制氢的影响

以γ-Al₂O₃为载体,采用等体积分步浸渍法制备了以Ni为活性组分,La、Ce、Fe、Cr、Co为助剂的催化剂M/γ-Al₂O₃,在固定床管式反应器中研究了M/γ-Al₂O₃催化剂的性能,考察了反应温度、水碳比和空速对氢产率的影响,并对催化剂进行XRD、SEM和BET表征。结果表明,NiLaCeFeCrCo/γ-Al₂O₃催化剂具有较好的催化性能,在反应温度700 ℃、水碳物质的量比10和空速6 min^-1的条件下,氢产率达到27.335 mol·mol^-1,并在300 min内表现出较好的活性,平均氢产率为21.966 mol·mol^-1。     

制备条件对NiMo/γ-Al2O3催化剂上萘加氢生成四氢萘的影响

采用等体积浸渍法制备加氢催化剂NiMo/γ-Al₂O₃,在悬浮床上考察不同的制备条件下NiMo/γ-Al₂O₃对萘加氢生成四氢萘的影响。结果表明,催化剂的制备条件对加氢活性有显著的影响,NiMo/γ-Al₂O₃催化剂的最佳制备条件为共浸渍法负载金属组分Ni和Mo,在500 ℃的温度下焙烧4 h。此条件下制备的催化剂上四氢萘的选择性高达95.2%。     

Pt/Pt-Ce/γ-Al2O3催化氧化甲苯研究

通过等体积浸渍法制备单贵金属Pt/γ-Al₂O₃和双金属Pt-Ce/γ-Al₂O₃催化剂,考察Ce对催化剂活性的影响,确定催化剂最优配比。结果表明,当Pt的负载量为质量分数0.5%时,Pt/γ-Al₂O₃催化活性最高;当Pt的负载量为质量分数0.2%,Ce的负载量为质量分数1.0%时,Pt-Ce/γ-Al₂O₃催化剂的催化活性最高。Pt-Ce/γ-Al₂O₃催化剂的甲苯转化率高于Pt/γ-Al₂O₃催化剂。随着Pt负载量增大,催化剂孔容、孔径减小。粉体式催化剂性能优于整体式催化剂,但差别不大;Ce的添加有助于催化剂活性的提升。     

低成本大比表面积γ-Al2O3的制备

以廉价无机铝盐硫酸铝为原料,氨水为沉淀剂,十二烷基硫酸钠为添加剂,采用简单沉淀法制备得到较大比表面积γ-Al₂O₃。通过N₂低温物理吸附-脱附、X射线衍射、红外光谱、热重、元素分析、扫描及透射电镜等,研究制备过程中沉淀温度、溶液pH值和添加剂用量对产物γ-Al₂O₃及其前驱体的晶相结构、形貌织构等性质的影响。结果表明,在沉淀温度75 ℃、硫酸铝浓度0.25 mol·L^-1、溶液pH=9.0、老化时间12 h和n(十二烷基硫酸钠)∶n[Al₂(SO₄)₃]=0.375∶1条件下,所得前驱体(拟薄水铝石)经600 ℃焙烧后,可获得大比表面积(416.65 m²·g^-1)γ-Al₂O₃,并且样品中因十二烷基硫酸钠添加,引入的S及Na等杂质含量极少。     

CO气相偶联合成草酸二甲酯Pd/α-Al2O3催化剂失活与再利用

作为合成气制乙二醇关键步骤之一,CO与亚硝酸甲酯合成草酸二甲酯备受关注。综述了近年来CO气相偶联合成草酸二甲酯Pd/α-Al₂O₃催化剂失活与再利用研究进展,探讨催化剂再利用工艺存在的问题,指出应根据在工业应用中出现的问题对Pd/α-Al₂O₃催化剂进行失活研究,在此基础上开发针对性的再生工艺;钯催化剂回收方面萃取法和吸附法逐渐成为研究重点,高效、低耗、短流程绿色工艺的开发是失活钯催化剂再利用的发展方向。     

K2CO3/γ-A12O3催化剂在棉籽油制备生物柴油中的应用

利用等体积浸渍法制备K₂CO₃/γ-A1₂O₃负载型固体碱催化剂,应用于棉籽油和甲醇酯交换反应制备生物柴油。对催化剂使用前的保存条件、水分、重复使用性能、游离脂肪酸影响以及失活和再生进行了分析。结果表明,固体催化剂K₂CO₃/γ-Al₂O₃具有较好的抗水性,酸度对催化剂影响明显,重复使用4次未经活化的催化剂,催化活性明显降低,催化剂应密封保存。K₂CO₃/γ-A1₂O₃负载型固体碱催化剂经济实惠且催化效果良好。     

浸渍法制备Pt-Sn/γ-Al2O3催化剂及其催化性能

采用等体积共浸渍法和分步浸渍法制备Pt-Sn/γ-Al₂O₃催化剂,并在固定床反应器上进行正丁烷脱氢实验研究。结果表明,与共浸渍法相比,分步浸渍法制备的催化剂表现出更高的催化活性。采用等体积浸渍法制备催化剂时,活性组分与载体之间会发生竞争吸附作用,这会影响活性金属组分在载体表面的分散度,进而影响催化剂活性。     

柠檬醛在La2O3/γ-Al2O3催化剂上的等温吸附

对柠檬醛-乙酸乙酯溶液中柠檬醛在La₂O₃/γ-Al₂O₃催化剂上等温吸附行为进行了研究。结果表明,30 ℃柠檬醛在La₂O₃/γ-Al₂O₃催化剂上的吸附动力学符合准二阶吸附动力学模型,吸附动力学方程为：1/q_t=2.350/t+0.063 3(R²=0.998 5)。（30~65） ℃柠檬醛在La₂O₃/γ-Al₂O₃催化剂上的等温吸附符合Langmuir方程,温度升高使柠檬醛的饱和吸附量增加,吸附热为32.19 kJ·mol^-1。     

亚硝酸甲酯羰基化合成草酸二甲酯废旧催化剂Pd/α-Al2O3中Pd的提取

采用HCl+H₂O₂混合溶液浸泡废旧催化剂Pd/α-Al₂O₃,滤掉氧化铝球颗粒,加入氨水沉淀滤液中Pd之外的微量杂质并过滤,在滤液中加入丁基钠黄药,形成Pd化合物沉淀,过滤,100 ℃烘干,350 ℃焙烧,生成PdO,纯度99.541%,再用H₂或CO在≥700 ℃下还原,得到纯Pd。该方法成本低,相对于王水法更环保、高效,Pd回收率>99.99%。     

Sn掺杂对Pt/Sn(x)-θ-Al2O3丙烷脱氢催化剂性能的影响

采用铝箔盐酸回流-油柱成型法制备了不同Sn掺杂量的Sn(x)-θ-Al₂O₃载体,并采用真空浸渍法制备了Pt/Sn(x)-θ-Al₂O₃催化剂。对制备的催化剂进行XRD、N₂物理吸附-脱附、NH₃-TPD、H₂-TPR和TG-DTA表征,研究了在载体中掺入助剂Sn对Pt/Sn(x)-θ-Al₂O₃催化剂结构及丙烷脱氢催化反应性能的影响。结果表明,在载体制备过程中掺入Sn,可以提高催化剂反应活性和产物选择性,当Sn掺杂质量分数为1.0%时,催化剂具有最优的丙烷脱氢反应性能,15 h的平均丙烷转化率为32.4%,平均丙烯选择性为95.5%。     

Nanosized γ-Al2O3 protective film for fluorescent lamps

Nanosized γ-Al₂O₃ particles were prepared by the sol–gel method with aluminum ion hydrolysis control performed by nitric acid. The as-prepared particles were mixed with deionized-water and stabilizer, and cycled in a high speed sand mill to form a stable γ-Al₂O₃ suspended slurry, which was then coated on the surface of the glass substrate to form a γ-Al₂O₃ protective film. Observations of SEM and visible transmission spectra show that a well-dispersed γ-Al₂O₃ slurry could be obtained after three-cycle grinding suitable to coat fluorescent lamp glass with a dense and uniform film of visible light transmission up to 95%.     

Combination of non-thermal plasma and heterogeneous catalysis for oxidation of volatile organic compounds: Part 2. Ozone decomposition and deactivation of γ-Al2O3

The role of ozone was studied for two different configurations combining non-thermal plasma (NTP) and heterogeneous catalysis, namely the use of a gas phase plasma with subsequent exposure of the effluent to a catalyst in a packed-bed reactor (post-plasma treatment) and the placement of the catalyst directly in the discharge zone (in-plasma catalysis). Non-porous and porous alumina and silica were deployed as model catalysts. The oxidation of immobilised hydrocarbons, toluene as a volatile organic compound and CO as an inorganic pollutant were studied in both operational modes.

While conversion and selectivity of hydrocarbon oxidation in the case of catalytic post-plasma treatment can be fully explained by the catalytic decomposition of O₃ on γ-Al₂O₃, the conversion processes for in-plasma catalysis are more complex and significant oxidation was also measured for the other three materials (-Al₂O₃, quartz and silica gel). It became obvious that additional synergetic effects can be utilised in the case of in-plasma catalysis due to short-lived species formed in the NTP.

The capability of porous alumina for ozone decomposition was found to be correlated with its activity for oxidation of carbon-containing agents. It could be clearly shown that the reaction product CO₂ poisons the catalytic sites at the γ-Al₂O₃ surface. The catalytic activity for O₃ decomposition can be partially re-established by NTP treatment. However, for practical purposes the additional reaction pathways provided by in-plasma catalytic processes are essential for satisfactory conversion and selectivity.