Thermal stability of Cu-K-V catalyst for diesel soot combustion

This paper reports a study on the thermal stability of a Cu-K-V catalyst, which showed particular promise for low temperature combustion of diesel particulate. Prolonged treatments were performed at high temperatures (400–1000°C) for periods up to 15 days under different gaseous atmospheres. The effect of such treatments on the catalyst composition was investigated by means of weight-decrease measurements and composition analysis (atomic absorption, X-ray diffraction, etc.), whereas the catalyst activity towards soot combustion was determined via thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The apparent activation energy of the soot combustion process was calculated for a collection of catalyst samples, thermally treated according to several different representative conditions, by the Ozawa method on the basis of the DTA results. Some of the thermal treatments (especially those performed at high temperatures: 900–1000°C) resulted in a reduction of the catalyst activity as shown by the increase of both the activation energy and the soot ignition temperature, as a consequence of the volatilisation of at least some of the active compounds of the catalyst itself (KCl, CuCl₂, etc.). Any periodic thermal regeneration of a catalytically-activated trap for diesel emissions (leading to such high temperatures) performed to eliminate any accumulated soot, has thus to be avoided by designing a trap capable of burning out all the soot produced at the diesel exhaust temperatures (< 400°C).     

CO低温氧化霍加拉特催化剂的研究

综述了CO低温氧化霍加拉特（Hopcalite）催化剂的活性影响因素、催化机理、催化剂失活原因以及最新研究进展,并展望了以后的发展方向。     

Mesoporous Cu–Mn Hopcalite catalyst and its performance in low temperature ethylene combustion in a carbon dioxide stream

Complete combustion of trace amounts of ethylene in food grade CO₂ over a Cu–Mn Hopcalite catalyst has been investigated. A mesoporous structure is identified in the catalyst. Low temperature calcined samples are found to be more active than the high temperature calcined ones. The presence of Cu²⁺ and Mn³⁺ is essential for the high activity of the catalyst. The Cu–Mn catalyst without a third component deactivates quickly in the reaction stream. However, doping with Al or Mg individually and with Ni–Al or Mg–Al simultaneously increases the lifetime. In situ DRIFTS measurements provide evidence that hydroxyl groups form and adsorb on Mn species. With the doping of Al, Mg and Ni ions, the amount of hydroxyl groups adsorbed reduces and the stability improves. Doping with Al and Mg simultaneously gives the best stability. A synergetic effect between CuO and amorphous Cu–Mn oxide phases is also confirmed.     

CrF3基催化剂的热稳定性及其对气相氟化反应的催化性能

研究了CrF₃基催化剂前驱体的热行为、催化剂的晶相和比表面积、孔容对催化剂活性的影响。结果表明，惰性气氛以及向前驱体中添加微量助剂可以提高其热稳定性；CrF₃基催化剂的活性相以非晶态存在；随着比表面积和孔容的增大，催化剂的活性提高。考察了CrF₃基催化剂对氟化HCFC-123合成HFC-125反应的催化性能。     

间二甲苯氨氧化催化剂工业化改进试验研究

以扩孔、灼烧后的改性硅胶作为载体,将含有V、Cr、Mo、P、K的活性组份物均匀浸渍于载体上,得到V-Cr-Mo-P-K系间二甲苯氨氧化催化剂(NT08#),在100 t/a间苯二甲腈中试装置进行生产试验,流化反应床特征反应温度(浓2#)390~400℃,投料比(摩尔比)空气∶氨∶间二甲苯=38∶7∶1,产品收率达到了91.3%。     

Thermal stability of palladium on ceria-doped alumina

Several palladium on alumina and ceria/alumina catalysts were prepared and oxidized in air between 400 and 1000°C. The metal dispersion was determined by hydrogen titration of adsorbed oxygen. Dispersions above 50% were maintained on 0.2% Pd/Al₂O₃ up to 900°C. Adding 5.0% ceria, or increasing the metal loading to 2.5%, greatly reduces the thermal stability of the palladium, such that the dispersion falls rapidly at 600°C. The rates of methane oxidation (moles of CO₂/g Pd h) at 250°C and 5% excess oxygen are nearly equal on 0.22–2.50% Pd/3.5–5.2% CeO₂/Al₂O₃, dispersion 14–42%, and 0.20–0.46% Pd/Al₂O₃, dispersion 59–86%, but are 10 to 20 times lower than the rate on 2.3% Pd/Al₂O₃, dispersion 11%. The lower rate of methane oxidation on ceria-promoted and highly dispersed palladium on alumina might be due to the conversion of the palladium into less active palladium oxide during reaction.     

钾碱对烧结型烃类蒸汽转化催化剂活性及稳定性的影响

利用常压微反-色谱装置,考察了烧结型烃类蒸汽转化催化剂钾碱加入方式和加入量对活性及稳定性的影响。结果表明,钾碱以钾的复盐(KAlSiO4)形式加入为好。它虽对活性有一定的抑制作用,但加入适量的钾,在对初活性影响不太大的情况下,有利于提高活性稳定性。     

磁性负载钌催化剂的制备及其在吗啉存在下的稳定性研究

通过碱性条件下二氯化铁和三氯化铁的共沉淀法制备Fe3O4,表面SiO2包覆后得到磁性纳米粒子Fe3O4-SiO2,经过硅烷偶联剂上的Si-OMe与磁性载体上的Si-OH的异相缩合,将不同结构的硅烷偶联剂接到载体上,实现了磁性载体的表面功能化.利用载体上的官能团与钌的络合,成功地制备出磁性负载钌催化剂.应用UV-Vis分...     

Rhodium supported in basic zeolite Y: A selective and stable catalyst for CO hydrogenation

Catalysts prepared by a condensation reaction of Rh(CO)₂(acac) within the supercages of zeolite Y made basic by treatment with NaN₃ are active for CO hydrogenation and selective for low-molecular-weight olefins and methanol. High partial pressures of CO (or CO + H₂) stabilize the catalyst. The predominant species in the catalyst are suggested to be rhodium carbonyl clusters trapped in the zeolite cages.     

New catalyst for the synthesis of poly(butylene terephthalate) with high thermo‐oxidative stability

In this paper we report the employment of Ti(acac)₂(O‐iPr)₂ (titanium bisacetylacetonate diisopropylate) as a novel catalyst for the synthesis of poly(butylene terephthalate) (PBT). Large scale synthesis of several polymers with the new catalytic system and with the standard catalyst Ti(O‐nBu)₄ (titanium tetra‐n‐butylate) have been performed in a 20 L pilot plant. In the optimized reaction conditions, Ti(acac)₂(O‐iPr)₂ has shown significantly higher activity than standard catalyst, Ti(O‐nBu)_4. Furthermore, a stabilized PBT has been synthesized in the presence of Ti(O‐nBu)₄ as catalyst with the addition of the stabilizer U626. Then, the stability of the synthesized polymers toward thermo‐oxidation has been tested in a forced circulating air oven. The polymers obtained in the presence of Ti(acac)₂(O‐iPr)₂ system showed higher stability towards thermo‐oxidation than stabilized and not stabilized PBT, synthesized in the presence of Ti(O‐nBu)₄. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

国产NDC-4型脱氢催化剂中铂含量分析方法的改进

采用自然基法测定国产NDC-4型脱氢催化剂中铂含量与本厂目前采用方法及UOP274-72法相比,结果准确可靠、简便快速,更适用于催化剂生产的中间控制分析,从而实现了国产NDC-4型脱氢催化剂中铂含量分析方法的改进。     

乙炔法合成醋酸乙烯酯催化剂活性影响因素分析及措施

从乙炔法合成醋酸乙烯酯反应机理出发,结合中国石化集团四川维尼纶厂生产实际情况,重点探讨了活性组分Zn(OAc)2含量、催化剂的配制过程、催化剂的粉化、催化剂床层温度等对催化剂活性的影响。提出改进催化剂载体结构、优化催化剂的配制、增加活性组分Zn(OAc)2含量、严格控制工艺条件等措施,从而提高产品产量。     

Improvement of anhydrous catalyst stability in acetylene dimerization by regulating acidity

BACKGROUND: Loss of the active CuCl component occurs during acetylene dimerisation to monovinylacetylene (MVA) catalysed by an anhydrous catalyst with the formation of a dark red precipitate. Acidic species can reduce the loss of CuCl but have an unfavorable influence on acetylene dimerisation. This study aims to determine the precipitate composition and regulate the acidity of the catalyst to find a balance between reaction rate, MVA selectivity and catalyst life. RESULT: The precipitate composition was 2CuCl·3C₂H₂·1/3CH₃CH₂NH₂·1/7C₃H₇NO, formed by the combination of DMF, CH₃CH₂NH₂, C₂H₂ and the [Cu]‐acetylene π‐complex, which is an intermediate in the reaction. From an overall consideration of the loss of CuCl, conversion of acetylene, and selectivity of MVA, the reaction temperature and acetylene space velocity were optimized at 65 °C and 200 h^?1, respectively. The introduction of HCl into the catalyst with a rate of 3.2 h^?1 could reduce CuCl loss by 73.5%, whereas conversion of acetylene was only lowered by 9.0%. CONCLUSION: Acidity regulation of the anhydrous catalyst by optimising the reaction temperature, acetylene space velocity, and rate of addition of HCl shows little negative effect on acetylene conversion and selectivity to MVA but can reduce CuCl loss significantly. © 2012 Society of Chemical Industry     

焙烧条件对乙苯脱氢催化剂耐水性能影响的研究

考察了焙烧条件对乙苯脱氢制苯乙烯催化剂耐水性能的影响。提高焙烧温度及延长焙烧时间有利于提高催化剂耐水浸泡能力，减缓水浸泡前后催化剂机械强度下降和磨耗率上升趋势。其原因可能是热处理条件的改变促进了Fe₂O₃和K₂O间的相互作用，形成了大量对水十分稳定的多铁酸钾KFe₁₁O₁₇固熔体，从而提高了催化剂的耐水性，并能与比表面、孔结构、XRD、Mōssbauer谱测定结果较好地关联。     

Thermal stability in a flow reactor containing a fixed catalyst bed

Biisk. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 4, pp. 68–74, July–August, 1990.     

S-RHT新型渣油加氢保护剂和脱金属催化剂的开发

根据我国加工中东进口原油的发展需要，开发出比第一代国产保护剂和脱金属催化剂以及同类进口剂综合性能更好的S-RHT新型保护剂和脱金属催化剂。其物化性能有显著改进，脱杂质活性和稳定性明显提高。     

负载型金属催化剂的热稳定机制

负载型金属催化剂是一类重要的催化材料,在石油炼制、环境保护以及材料合成等领域起着重要的作用。然而,由于活性金属在反应环境下容易烧结团聚,以致活性降低乃至失活,因此,如何提高其热稳定性成为负载型金属催化剂研究的一个关键问题。概述了催化剂的金属团聚成因及其稳定机制。简要介绍了Ostwald效应以及颗粒合并长大两种团聚模型,从热力学角度解释了导致催化剂烧结团聚的原因。总结了现阶段几种提高负载型金属催化剂热稳定性能的方法,具体包括以包覆封装隔离为原理的物理方法,以及以形成化学键为基础的化学方法,可为进一步开发高热稳定性的负载型金属催化剂提供借鉴。     

Influence of feed components on the activity and stability of cobalt molybdenum alumina metathesis catalyst

Alkene metathesis plays a vital role industrially in the upgrading of low value alkenes to higher value alkenes such as linear internal alkenes in the C₁₀–C₁₈ range. These in turn find application as feedstock for manufacturing of surfactants and detergents. Industrial alkene cuts contain component(s) that might be detrimental to the catalyst active sites during the metathesis reaction leading to catalyst deactivation. The focus of this study was to investigate the effect of some of the components present in typical low value feed streams on the activity and stability of a CoO/MoO₃/Al₂O₃ catalyst. The results indicated that the feed composition does have a major influence on the metathesis reactivity of the catalyst. Pure 1-octene (98%), which was used as a reference feed was spiked with various components that had a concentration of 100 ppm. Results revealed a trend in terms of the severity of the component that deactivated the catalyst to be water > methylcyclopentadiene dimer > methylcyclopentane > toluene > 2-pentanone > 2-methyl-1,5-hexadiene > 2-methyl-1-hexene > butanol.

A study was also undertaken to examine whether the component (methylcyclopentadiene dimer as an example) that deactivates the catalyst is a temporary or permanent poison. Results showed that methylcyclopentadiene dimer is a temporary poison. The carbonaceous deposits (oligomers) formed during the reaction seem to be the primary cause of catalyst deactivation. However, the catalyst deactivation mechanism in the presence of water in 1-octene feed is mostly linked to the molecular structural change of the catalyst rather than accumulation of carbonaceous deposits on the surface of the catalyst.     

Activated carbon supported Ni-Ca: Influence of reaction parameters on activity and stability of catalyst on methane reformation

The objective of the present work was to study the influence of some reaction parameters (temperature, chemical nature of pre-treatment gas, mass catalyst) on the yield of methane reforming with carbon dioxide on Ni (5%)-Ca (1%)/AC at atmospheric pressure. The obtained results show that the best system was pre-treated under He flow at 650 °C and then following the reaction at the same temperature. It was also detected that Ca plays a co-support role inhibiting the deactivation of catalyst at long periods of reaction. It can be concluded that it is possible to employ activated carbon as support for methane dry reformation obtaining representative methane conversions up to 40% at mild experimental conditions.     

国内甲硫醇催化剂现状

介绍了五种甲硫醇的生产工艺用催化剂,尤其是硫化氢-甲醇法、甲醇-二硫化碳法和高硫合成气法用催化剂的制备工艺和性能。分析了添加不同的助剂对催化剂的性能的改善。三种工艺路线生产甲硫醇催化剂中主体活性组分都是ⅥB族过渡金属元素W和Mo,常用的助催化剂为K,载体为具有一定孔特性的二氧化硅和氧化铝。