KOAc/NaY催化合成邻甲基苯甲醚

以KOA c/NaY为催化剂,在连续流动固定床反应器内,邻甲基苯酚(OC)与碳酸二甲酯(DMC)经过气固相催化反应合成了邻甲基苯甲醚(OM)。考察了内、外扩散对KOA c/NaY催化剂活性的影响。实验结果表明,当气流线速度大于30cm/m in时可消除外扩散对合成反应的影响;当KOA c/NaY催化剂的平均粒径在0.30~0.75mm(20~80目的颗粒)时能消除内扩散对合成反应的影响。在消除内、外扩散效应后,还考察了反应温度、原料配比、空速对合成反应的影响,得到较佳的反应条件:催化剂5mL,反应温度548K,反应压力0.6M Pa,空速0.6h-1,n(DMC)∶n(OC)=1,在线评价时间7h。在此条件下,OC的转化率高达85.7%,OM的选择性大于99%。     

Methane oxidation over vanadium-modified Pd/Al2O3 catalysts

Three different vanadium-modified Pd/Al₂O₃ catalysts were prepared and tested as catalysts for the deep oxidation of methane. Vanadium was added to the palladium catalyst by incipient wetness of palladium catalyst in order to modify its properties and improve its thermal stability and thioresistance. The behaviour of vanadium-modified catalysts depends on the concentration of this compound, being 0.5 wt.% the optimum amount. However, when strong catalyst poisons are present in the gas (SO₂), these modified catalysts do not show a better performance than unmodified catalyst. Bimetallic catalysts were tested with and without further reduction, being observed that reduced bimetallic catalysts perform worse than the non-reduced ones.     

载体比表面积及孔径对Nb_2O_5/α-Al_2O_3催化剂酸性及反应性能的影响

采用浸渍法制备了Nb2O5/α-A l2O3催化剂(简称催化剂)并用于环氧乙烷水合制乙二醇的反应,通过控制α-A l2O3载体中致孔剂的含量来调变载体的孔径、孔分布及比表面积;采用吡啶吸附红外光谱、氨程序升温脱附法研究了载体的比表面积及孔径对催化剂酸性及反应性能的影响。实验结果表明,产物的选择性受扩散因素及催化剂酸性的影响,而催化剂的酸量、酸密度可以通过载体的孔径及比表面积的变化加以调控。比表面积较小及孔径较大的载体对催化剂催化环氧乙烷水合制乙二醇的反应较为有利。当载体的比表面积小于0.80m2/g、孔径为4.00~8.00μm时,在反应温度160℃、反应压力1.5M Pa、n(H2O)∶n(EO)=22、液态空速25h-1的条件下,环氧乙烷的转化率大于99.8%,乙二醇的选择性超过89.9%。     

CeO2对RuO2／γ-A12O3催化剂湿式氧化降解苯酚性能的影响

采用浸渍法制备了RuO2／γ-A12O3和RuO2／CeO2／γ-A12O3催化剂，并利用XRD、SEM和XPS对催化剂进行了表征，研究了Ce的加入对RuO2／γ-A12O3催化剂表面分散性和催化剂表面元素Ru，O和Ce化学态的影响，同时考察了RuO2／γ-A12O3和RuO2／CeO2／γ-A12O3催化剂湿式氧化降解苯酚的活性，并深入探讨了Ce对RuO2／γ-A12O3催化剂的助催化作用。结果表明：Ce掺杂改性后，使催化剂表面Ru的化学态降低、表面氧空位增加，并且活性组分Ru的分散性增加，从而使RuO2／CeO2／γ-A12O3催化剂的活性提高，因此Ce起到了显著的助催化作用。     

一种制氢预转化催化剂还原的新方法

对上海高桥分公司2×10~4m~3/h(标准状态)制氢装置原设计的预转化催化剂还原流程进行了改进。先跳开预转化反应器,利用转化炉制取氢气,再用自产的高纯氢气代替重整氢,对预转化催化剂进行单独升温还原,避免了催化剂在还原初期因发生甲烷化反应而超温失活的问题,使催化剂具有更好的活性和稳定性。     

凝胶成型法制备加氢催化剂载体的研究与工业化生产

采用凝胶成型法制备加氢催化剂载体，并进行了工业放大试验。通过BET、NH3-TPD、H2-TPR等表征手段及实际的加氢反应性能评价对凝胶成型法制备的载体及加氢催化剂与常规方法进行对比分析，结果表明，采用凝胶成型法所制得的载体及催化剂均具有较高的孔体积和比表面积、较低的堆密度，其机械强度可满足工业要求，总酸量及中强酸酸量得到提升，催化剂活性组分与载体强结合力得到削弱，金属利用率提高，应用性能明显优于传统方法制备的加氢催化剂载体。通过该方法完成了加氢催化剂载体的工业生产，所生产的载体应用于天津院THDS-3加氢精制催化剂取得了良好的工业应用效果。     

Cd-ZSM-5沸石催化剂的制备、表征和芳构化催化性能

采用离子交换、浸渍和混合三种方法制备镉改性ZSM-5沸石催化剂,考察了改性方法和镉含量对催化剂的表面酸性和Cd状态以及芳构化性能的影响。结果表明,加入镉降低了B酸性,Cd~(2+)与沸石结合形成了L_(1612)酸中心,其生成量取决于改性方法和Cd含量,并与芳构化活性提高有直接关系。     

Sulfated zirconia catalysts: Are Brønsted acid sites the source of the activity?

The thermal decomposition products of pyridinium sulfate differ from those of pyridinium sulfate supported on zirconia which in turn differs from that of pyridine adsorbed on a sulfated zirconia. Unsupported pyridinium sulfate decomposes to produce pyridine and sulfuric acid, and these subsequently react to produce oxides of carbon and sulfur. Zirconia that is sulfated and then exposed to pyridine does not release detectable amount of pyridine during heating in an inert gas; rather the pyridine undergoes oxidation reduction reactions simultaneously to release CO₂ and sulfur compounds. Pyridinium sulfate supported on zirconia decomposes upon heating to release pyridine and sulfuric acid, which reacts with the zirconia. The desorption of pyridine in one case and only CO₂/SO_x in the other case suggests that sulfated zirconia does not contain Brønsted acidity that can form pyridinium sulfate.     

聚合物载体－稀土金属络合物的研究 ⅩⅢ．聚［苯乙烯－甲基丙烯酸β（甲基亚硫酰基）乙酯］的结构与其稀土金属络合物催化丁二烯聚合的活性

从测得的竞聚率计算了单体链节在聚［苯乙烯－甲基丙烯酸β（甲基亚硫酰基）乙酯］（ＰＳＭ）中的序列分布。苯乙烯（Ｓ）或甲基丙烯酸β（甲基亚硫酰基）乙酯（Ｍ）的长序列的概率随着ＰＳＭ中相应单体含量的增加而增加。对于Ｓ和Ｍ摩尔分数大致相等的ＰＳＭ，单体链节的长序列分布函数值相接近。用与此结构相近的ＰＳＭ合成的稀土金属络合物，其催化活性不佳。在Ｍ短序列分布和Ｓ长序列分布较高的情况下，络合物的催化活性最好。所得聚丁二烯的微观结构与ＰＳＭ中单体单元的分布无关。     

Nitric oxide reduction and carbon monoxide oxidation over carbon-supported copper-chromium catalysts

Carbon supported copper-chromium catalysts are shown to be very active for both the reduction of nitric oxide with carbon monoxide and the oxidation of carbon monoxide with oxygen. Mixed copper-chromium oxide active phases have good activity in the simultaneous removal of nitric oxide and carbon monoxide from exhaust gases. The influence of several catalyst variables has been investigated. The activity per volume of catalyst increases with increasing loading, while the intrinsic activity shows a maximum around C/M=100−50. An optimum catalyst for nitric oxide reduction and carbon monoxide oxidation has a copper/chromium ratio of 2/1. The apparent activation energy for the carbon monoxide oxidation over carbon supported copper-chromium catalysts is 77 kJ/mol, suggesting that the Cu---O bond rupture is the rate-limiting process. The reduction of nitric oxide takes place at higher temperatures. Since all catalysts have a low selectivity for molecular nitrogen formation at lower temperatures, the dissociation of nitric oxide is probably rate determining, resulting in a slightly reduced catalyst system. In an excess of carbon monoxide the reaction is first-order in nitric oxide and zero-order in carbon monoxide. Moisture inhibits the reaction by reversible competitive adsorption, whereas carbon dioxide does not. Oxygen completely inhibits the reduction of nitric oxide due to the more rapid reoxidation of the catalytic sites compared to nitric oxide. Therefore, the reduction of nitric oxide takes place only when all oxygen has been converted and, hence, is shifted to higher temperatures. As a possible consequence, the production of nitrous oxide is reduced. Nitric oxide and molecular oxygen react preferentially with carbon monoxide, so, in an excess of oxidizing component, gasification of the carbon support occurs at higher temperatures after carbon monoxide has been completely consumed.