Reforming of CH4 with CO2 over Rh/H-Beta:Effect of Rhodium Dispersion on the Catalytic Activity and Coke Resistance

The effect of Rh dispersion on reforming of CH₄ with CO₂ over H‐Beta supported Rh catalysts has been investigated. The CH₄ and CO₂ conversion over the catalysts increase with increasing Rh loading from 0.5 wt% to 4.0 wt% in the reaction temperature range of 823–1123 K. The high TOF of CH₄ over 0.5 wt% and 1.0 wt% Rh/H‐beta may be attributed to high dispersion of rhodium species. The catalysts before and after the reaction were characterized by XRD, TEM, and TG‐DTA and the results indicate the catalysts with Rh loading of 0.5 wt% and 1.0 wt% exhibiting high resistance to coke. Under controllable conditions, we confirm that the coke is originated from methane dissociation and can be substantially oxidized by active oxygen species dissociated from the adsorbed carbon dioxide on the catalyst with high dispersion of Rh species.     

K助剂对Pt-Sn-K/γ-Al2O3催化剂上C16正构烷烃脱氢反应的影响

 以络合真空浸渍法制备了 Pt-Sn-K/γ-Al2O3 催化剂. 采用吡啶吸附红外光谱、CO脉冲吸附、程序升温还原、热重及程序升温氧化等手段对催化剂进行了表征, 研究了 K 助剂对 Pt-Sn-K/γ-Al2O3 催化剂结构及其催化 C16 正烷烃临氢脱氢反应性能的影响. 结果表明, K 的引入减弱了 SnOx 和 Al2O3 间的相互作用, 促进了 Pt 对 SnOx 的还原, 并导致催化剂的脱氢反应活性降低. K 的加入还减少了强酸中心数目, 一方面减少了催化剂酸性位上的副反应, 提高了产物选择性; 另一方面提高了催化剂的抗积炭能力, 催化剂稳定性有所改善. 但过量的 K 助剂减弱了催化剂的金属位-酸性位的协同作用, 使得催化剂活性和稳定性均有所降低.     

Metal Supported Zeolite for Heavy Aromatics Transalkylation Process

Aiming at improving the catalytic activity, benzene product purity, and catalyst stability during heavy transalkylation processes, strategies invoking startup procedures and catalyst system designs are summarized and discussed in this review. In particular, recent advances in the developments and catalytic performances of the on-line sulfiding technique, the selective pre-coking startup procedure, and a versatile dual-bed catalyst system design were compared and discussed.     

Influence of potassium on the properties of steam reforming catalysts

The influence of K₂O on the amounts of chemisorbed hydrogen on a Ni catalyst, the catalyst activity and its resistance to coking were measured. Introducing potassium into the commercial catalyst (not into the support) appeared to enhance its resistance to coking. The best catalytic characteristics was noticed for a system containing ~0.5 wt. % K₂O. The investigations show a good agreement between the resistance to coking obtained by the temperature-programmed reaction (TPReaction) method and by the traditional thermogravimetric method. This revised version was published online in August 2006 with corrections to the Cover Date.     

离子液体催化剂用于煤焦化苯深度脱硫制无硫苯

从扩大有机合成用苯的需求出发,采用研制的离子液体催化剂考察了煤焦化苯深度脱硫制无硫苯的过程。结果表明：N-甲基咪唑硫酸氢盐[Hmim][HSO₄]离子液体催化剂脱噻吩效果与其酸函数值有关。本文采用Hammett指示剂测定离子液体的酸函数H₀,并得出：在-4至-12的范围,离子液体催化剂可以使煤焦化苯噻吩脱至0. 5mg/L以下。与固体酸催化机理相似,酸量和酸强度一定的离子液体催化剂通过Friedel-Crafts反应形成烷基噻吩等,与苯的物性拉开距离,对苯的分离精制是必不可少的,但是过多、过强的[Hmim][HSO₄]酸值也更有利于苯-噻吩-烯烃共聚合等副反应的发生,从而影响离子液体催化剂重复使用的寿命。本研究利用煤焦化苯脱硫反应形成的噻吩衍生物作为提供电荷流通的聚合物,将反复使用后性能不佳的离子液体成分等作为“受电子型”和“给电子型”的掺杂剂,进行导电（抗静电）材料的制备。结果显示：对煤焦化苯脱硫形成的噻吩衍生物等可以用于掺杂导电材料的试制。     

Coking during ethylene glycol oxidation to glyoxal on a silver catalyst

The influence of major parameters of ethylene glycol oxidation to glyoxal on a silver catalyst on catalyst coking has been studied. On the basis of experimental data obtained, methods decreasing the coking have been suggested.     

丝光沸石催化剂的结焦失活研究

用ＧＣ－ＭＳ，ＨＮＭＲ和元素分析研究了结焦的钯／氢型丝光沸石催化剂上焦炭的分子性质，用ＦＴ－ＩＲ，ＴＰＤ，ＴＰＯ，微孔分析和活性评价等考察了催化剂结焦前后性质的变化。结果表明，催化剂上可溶性焦炭为二至四环的多环芳烃，它们滞留在分子筛孔内起覆盖活性中心的作用，且是进一步生成高碳氢比焦炭的前身物，结炭反应主要发生在酸中心上，随着结炭量的增加，催化剂上Ｂ中心大量减少，表面积和孔体积亦相应减小，与焦炭分子     

Ni系水蒸气转化催化剂上积炭和消炭机理的探讨

根据作者动力学研究结果探讨了４６０～５５０℃，１．０１×１０５Ｐａ下Ｃ７Ｈ１６在国产Ｎｉ系催化剂上水蒸气转化过程中的积炭和随后水蒸气消炭的机理，提出了相应的机理及其表达式．认为积炭速率的决定步骤是吸附态的Ｃ７Ｈ１６在Ｎｉ表面的深度脱氢，消炭过程的决定步骤是须炭于浓度差推动下在Ｎｉ晶粒中的溶解扩散．提出了控制和消除Ｎｉ表面上须炭核的生成及长大是提高催化剂抗积炭性能的关键．     

MFT改质反应ZSM-5分子筛催化剂结焦行为的研究 Ⅱ.正庚烷和MFT模型混合物

通过参数估计和模型筛选，获得了正庚烷和ＭＦＴ模型混合物在ＺＳＭ５分子筛催化剂上的结焦动力学方程，模型能够和实验数据较好地关联，最大相对误差不超过±２０％。用正庚烷模拟ＦＴ合成产物中碳数小于１１烃在ＺＳＭ５分子筛催化剂上的结焦，用ＭＦＴ模型混合物来模拟ＦＴ合成产物中Ｃ＋１２烃在ＺＳＭ５上的结焦，则：Ｃ＝３１．５３ｅ１４８９６．７４ＲＴｔ０．３３ｆ０．２２１＋１７３．１９ｅ１７６２８．１３ＲＴｔ０．２０ｆ０．２９２能够较准确地预测ＭＦＴ中试改质反应器入口附近分子筛催化剂上的焦含量。结合本研究的第一部分，对不同反应原料在ＺＳＭ５上的结焦行为进行了比较，表明ＺＳＭ５上的结焦很可能是一个扩散控制过程。     

焦油催化裂化催化剂积炭失活的实验研究

对白云石、石灰石作用下生物质热解焦油催化裂化过程中的积炭失活问题进行了研究，考察了较长反应时间内催化剂积炭量和焦油转化率的变化情况。最长运行时间32 h，所得积炭质量分数为3%～15%，焦油转化率下降到70％左右。对不同来源焦油的生焦性、催化裂化反应条件等对积炭形成的影响作了考察，并从动力学角度对催化活性与积炭量之间的关系进行了分析，得到了单层积炭和多层积炭阶段线性和指数形式的关联式。