CO波动对碳二前加氢反应的影响及应对措施

阐述了裂解气中CO生成机理、波动原因,论述了CO波动对等温列管式碳二前加氢反应器催化剂活性、选择性加氢的影响。根据实际经验提出了裂解炉投退炉期间控制裂解气中CO浓度波动的措施,以及碳二前加氢反应器相应的精细调整方法。     

乙烯装置碳二前加氢工艺技术及运行稳定性研究

本文介绍了乙烯装置中使用的碳二前加氢工艺技术,并针对前脱丙烷前加氢工艺技术的特点,分析了影响碳二前加氢反应器运行稳定性的因素,提出了工业生产中避免反应器波动的操作方法。     

减少乙烯装置碳二前加氢工艺中CO的影响

分析了碳二前加氢工艺中CO浓度对加氢反应的影响，讨论了CO的生成因素，提出了减少CO生成量及控制CO浓度波动的有效措施：加强注硫操作，降低裂解炉投料温度，防止甲醇进入裂解炉等，以保证装置平稳操作。     

乙炔前加氢反应器运行稳定性的研究

针对乙烯生产前脱丙烷前加氢工艺技术的特点,分析了影响乙炔前加氢反应器稳定性的因素,提出了工业生产中避免反应器波动的操作方法。     

前脱丙烷前加氢催化剂的工业应用

简述了乙烯装置中前脱丙烷前加氢工艺的特点和国产前加氢催化剂在大庆石化进行工业应用试验的情况。国产催化剂的各项指标全面达到或超过了同类进口催化剂的水平，尤其在抗CO波动能力等方面具有明显优势。     

大庆石化乙烯装置应用数学建模估算碳二加氢催化剂反应活性方法研究

乙炔前加氢反应系统中,催化剂活性与物料中的CO浓度密切相关。通过应用数学建模方法,提出一种三角函数来描述CO浓度对催化剂活性的影响程度,能够根据CO浓度对催化剂活性进行定量分析,并根据CO的波动范围提供操作依据,进而指导生产。     

继续进行炼油企业结构调整 加快我国加氢工艺技术发展

指出近年来我国炼油企业结构调整已初见成效，加氢工艺技术获得了较快发展，预测21世纪初将是加氢工艺大展宏图的时代，应充分利用石油资源加快我国加氢工艺技术发展；并介绍了重点研究开发和推广应用的各项加氢技术。     

碳二脱炔在高浓度CO时的稳定性研究

部分碳二前加氢脱炔流程的反应物中CO浓度过高，增加了工业运行的难度。本文在催化剂配方优化的基础上，采用工业侧线实验方式进行了模拟评价。实验以前脱乙烷前加氢反应为研究对象，研究了在CO浓度升高的情况下，催化剂主要性能参数的变化。结果表明该剂具有稳定脱除乙炔的优势，反应放热稳定，有利于降低工业操作难度。     

石油树脂加氢技术的现状

对石油树脂国内外现状，石油树脂加氢用的原料，加氢工艺技术及加氢石油树脂的应用作了简要评述，对石油树脂加氢技术的发展提出了建议。     

超临界二氧化碳介质中的催化加氢反应

综述了超临界二氧化碳（SCCO2）介质中的催化加氢反应，包括不对称加氢、不饱和醛／酮加氢、油脂加氢、CO加氢（氢甲酰化反应）、CO2加氢和硝基化合物加氢。     

大庆乙烯新区装置工艺特点分析

大庆乙烯新区装置采用了前脱丙烷、前加氢以及乙烯机开式热泵等节能工艺,使装置总能耗降低。由180 kt/a改造为270 kt/a的过程中,充分利用原有设施,降低投资。     

催化CO/H2O还原芳香硝基化合物制芳胺的研究进展

CO／H2O还原芳香硝基化合物制芳胺是1978年首次被发现。所使用的催化剂为过滤金属羰基化合物有些可以在常温常压下完成反应，并具有很好的选择性，在反应完成后可将催化剂从反应产物中分离这项技术可以做为加氢还原重要补充。反应过程的常压化、催化剂的分离将成为这项技术研究重点。这项新技术将有广阔的工业前景、有24篇参考文献。     

乙烯分离流程技术方案的研究探讨

综述了乙烯分离的装置中主要的顺序分离、前脱乙烷和前脱丙烷三大分离流程,并对各个分离流程的节能技术进行了比较。     

二氧化碳催化还原剂及反应机理研究

催化还原是二氧化碳资源化利用的有效途径之一。文章综述了CO2加氢还原过程中采用的还原剂,主要为氢气(H2),甲烷(CH4)等,分析了CO2催化还原机理,详细探讨了CO2与H2反应生成甲醇、二甲醚等的催化剂及反应机理,并且提出了CO2催化还原技术发展前景。     

First-principles analysis of the hydrogenation of carbon monoxide over palladium

The reaction paths for the hydrogenation of CO to methanol over Pd_x (x = 1–4 and 19) cluster models were examined using first-principle density functional quantum chemical calculations. The predicted adsorption energies for the most favorable binding modes for CO, H₂, HCO, H₃CO, CH₃OH, C, O and H on a Pd₁₉ model Pd(111) clusters were -147, -62, -340, -51, -195, -33, -610, -349 and -251 kJ/mol, respectively. The most favorable modes for CO, CH₃O, H, C and O on Pd(111) were all found to be the 3-fold fcc site. The most favorable modes for the formyl and formaldehyde surface intermediates at low coverage were the 3-fold (ζ²μ³), and the di-σ sites, respectively. At higher surface coverages, however, the atop ζ¹ (C) and the π modes for the formyl and formaldehyde intermediates were more likely. The computed adsorption energies were subsequently used to compute overall reaction energies for the hydrogenation of CO to methanol. The initial hydrogenation of CO to the ζ¹ (C) HCO intermediate was found to be +52 kJ/mol endothermic and has been speculated as a possible rate-limiting step. The remaining surface hydrogenation steps become increasingly more exothermic as more hydrogen was added. The elementary steps of formyl to formaldehyde, formaldehyde to methoxide and methoxide to methanol were computed to be -9, -26 and -33 kJ/mol, respectively. The overall energy for CO dissociation was found to be highly unlikely at +260 kJ/mol and a clear indication that methanation and chain growth chemistry is not very likely over Pd. The most favorable reaction coordinate for the hydrogenation of CO to the ζ¹ (C) formyl intermediate was that which proceeds over a single Pd site where there is a migratory insertion of the CO into a Pd–H bond. The barrier for this path was computed to be +78 kJ/mol on the Pd₁₉ cluster. There was a very weak dependence on cluster size. This is a likely indication that this reaction is structure insensitive. A second path which involved the coupling of H and CO over a bridge site was found to be +130 kJ/mol which is less likely, but may also occur under different conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Photo-activated metal carbonyl complexes as stereoselective catalysts for the homogeneous hydrogenation of dienes

Significantly increased activity of Cr(CO)₆ was achieved for the stereoselective homogeneous hydrogenation of methyl sorbate andtrans,trans-conjugated fatty esters at ambient temperature and pressure by exposing the catalyst to UV irradiation (3500 Å) in a solvent mixture of cyclohexane-acetonitrile (20:1). In this solvent mixture, methyl sorbate was converted quantitatively at ambient conditions into methylcis-3-hexenoate, and methyltrans-9,trans-11-octadecadienoate into methylcis-10-octadecenoate (99.9%). These products are expected by 1,4-addition of hydrogen. Under these conditions no hydrogenation of methyl linoleate occurred. Under the same conditions, cycloheptatriene-Cr(CO)₃ showed lower activity than Cr(CO)₆, and Mo(CO)₆ and mesitylene-Mo(CO)₃ showed no significant activity toward conjugated substrates. When Cr(CO)₆ and Mo(CO)₆ were irradiated at 2537 Å they caused the geometric isomerization of methyl sorbate without hydrogenation, but had no effect on methyl linoleate. A hydrogenation mechanism is proposed for Cr(CO)₆ that involves CH₃CN- and H₂-Cr(CO)₃ complexes as intermediates for the stereoselective 1,4-addition of hydrogen totrans,trans-conjugated dienes.     

The hydrogenation of CO over molybdenum/alumina in the presence of ethylene; coupling of olefin metathesis and CO hydrogenation

Three reactions, CO hydrogenation, metathesis of C₂H₄ and CO hydrogenation in the presence of C₂H₄, have been investigated on Mo(+2)/Al₂O₃ under identical experimental conditions. The products of hydrogenation reactions were methane, ethylene and propylene. The results show that the initial rate of propylene formation for CO hydrogenation in the presence of ethylene is much larger, by a factor of 7, than the sum of the rate of propylene formation for CO hydrogenation and metathesis alone. Furthermore, it was found that¹³C labelled propylene was formed in the hydrogenation of¹³CO in the presence of ethylene. These results, taken as a whole, suggest that the same intermediate is formed in both CO hydrogenation and metathesis of ethylene, and that these intermediates can be either incorporated into ethylene and higher hydrocarbons by polymerization or incorporated into ethylene to form propylene via olefin metathesis.     

CO Poisoning of Ethylene Hydrogenation over Pt Catalysts: A Comparison of Pt(111) Single Crystal and Pt Nanoparticle Activities

The ethylene hydrogenation reaction was studied on two platinum model catalyst systems in the presence of carbon monoxide to examine poisoning effects. The catalysts were a Pt(111) single crystal and lithographically fabricated platinum nanoparticles deposited on alumina. Gas chromatographic results for Pt(111) show that CO adsorption reduces the turnover rate from 10¹ to 10^-2 molecules/Pt site/s at 413 K, and the activation energy for hydrogenation on the poisoned surface becomes 20.2 ± 0.1 kcal/mol. The activation energy for ethylene hydrogenation over Pt(111) in the absence of CO is 10.8 kcal/mol. The Pt nanoparticle system shows the same rate for the reaction as over Pt(111) in the absence of CO. When CO is adsorbed on the Pt nanoparticle array, the rate of the reaction is reduced from 10² to 10⁰ nmol/s at 413 K. However, the activation energy remains largely unchanged. The Pt nanoparticles show an apparent activation energy for ethylene hydrogenation of 10.2 ± 0.2 kcal/mol in the absence of CO and 11.4 ± 0.6 kcal/mol on the CO-poisoned nanoparticle array. This is the first observation of a significant difference in catalytic behavior between Pt(111) and the Pt nanoparticle arrays. It is proposed that the active sites at the oxide--metal interface are responsible for the difference in activation energies for the hydrogenation reaction over the two model platinum catalysts.     

Ethylene hydroformylation and carbon monoxide hydrogenation over modified and unmodified silica supported rhodium catalysts

Ethylene hydroformylation and carbon monoxide hydrogenation (leading to methanol and C₂-oxygenates) over Rh/SiO₂ catalysts share several important common mechanistic features, namely, CO insertion and metal–carbon (acyl or alkyl) bond hydrogenation. However, these processes are differentiated in that the CO hydrogenation also requires an initial CO dissociation before catalysis can proceed. In this study, the catalytic response to changes in particle size and to the addition of metal additives was studied to elucidate the differences in the two processes. In the hydroformylation process, both hydroformylation and hydrogenation of ethylene occurred concurrently. The desirable hydroformylation was enhanced over fine Rh particles with maximum activity observed at a particle diameter of 3.5 nm and hydrogenation was favored over large particles. CO hydrogenation was favored by larger particles. These results suggest that hydroformylation occurs at the edge and corner Rh sites, but that the key step in CO hydrogenation is different from that in hydroformylation and occurs on the surface. The addition of group II–VIII metal oxides, such as MoO₃, Sc₂O₃, TiO₂, V₂O₅, and Mn₂O₃, which are expected to enhance CO dissociation, leads to increased rates in CO hydrogenation, but only served to slow the hydroformylation process slightly without any effect on the selectivity. Similar comparisons using basic metals, such as the alkali and alkaline earths, which should enhance selectivity for insertion of CO over hydrogenation, increased the selectivity for the hydroformylation over hydrogenation as expected, although catalytic activity was reduced. Similarly, the selectivity toward organic oxygenates (a reflection of the degree of CO insertion) in CO hydrogenation was also increased.     

Cr(CO)3-complexed,silica-bonded polyphenylsiloxane as a stereoselective catalyst for hydrogenation of sorbate and soybean methyl esters

A silica-bonded complex was prepared by reacting polyphenylsiloxane with silylated Chromosorb and then with Cr(CO)₆. This complex catalyzed stereoselective hydrogenation of sorbate tocis-3-hexenoate. Soybean methyl esters were hydrogenated at 210 C in cyclohexane to form products high incis unsaturation. The recovered catalyst could be recycled once with methyl sorbate. IR showed decreased Cr(CO)₃ in the recovered catalysts, and the hydrogenation products contained inactive Cr.