Continuous slurry hydrogenation of soybean oil with copper-chromite catalyst at high pressure

Selective hydrogenation of soybean oil to reduce linolenic acid is accomplished better with copper than with nickel catalysts. However, the low activity of copper catalysts at low pressure and the high cost of batch equipment for high-pressure hydrogenation has precluded their commercial use so far. To evaluate continuous systems as an alternative, soybean oil was hydrogenated in a 120 ft × 1/8 in. tubular reactor with copper catalyst. A series of hydrogenations were performed according to a statistical design by varying processing conditions: oil flow (0.5 L/hr, 1.0 L/hr and 2.0 L/hr), reaction temperature (180 C and 200 C), hydrogen pressure (1,100 psig and 4,500 psig) and catalyst concentration (0.5% and 1.0%). An iodine value (IV) drop of 8–43 units was observed in the products whereas selectivity varied between 7 and 9. Isomerization was comparable to that observed with a batch reactor. Analysis of variance for isomerization indicated interaction between catalyst concentration and hydrogen pressure and between catalyst concentration and temperature. The influence of pressure on linolenate selectivity was different for different temperatures and pressure. Hydrogenation rate was significantly affected by pressure, temperature and catalyst concentration.     

The effect of oxygen and the reduction temperature of the Pt/Al2O3 catalyst in enantioselective hydrogenation of 1-phenyl-1,2-propanedione

The effect of oxygen and catalyst reduction temperature in enantioselective hydrogenation of 1-phenyl-1,2-propanedione over commercial Pt/Al₂O₃ catalyst was investigated. Dichloromethane was used as solvent. The catalyst was modified in situ with (−)-cinchonidine. Relatively high enantiomeric excesses (65%) of (R)-1-hydroxy-1-phenyl-2-propanone were obtained with the solvent used as received, i.e. containing traces of dissolved oxygen and other impurities. Dichloromethane dissociated partially on the Pt/Al₂O₃ surface causing desorption of methane, ethene and HCl from the catalyst during TPD according to mass spectrometric analysis. Under anaerobic conditions the reaction rate was low giving only about 40% enantiomeric excesses of (R)-1-hydroxy-1-phenyl-2-propanone. When injecting 5 mm³ of oxygen into the reactor a beneficial effect was observed (i.e. higher reaction rate and enantiomeric excess) in comparison with anaerobic conditions. Poisoning effect of oxygen was observed when injecting 500 mm³ of oxygen into the reactor. Effect of catalyst reduction temperature was studied at three different temperatures (170, 400 and 455°C). Highest reaction rates and enantiomeric excesses were obtained with the catalyst reduced at 400°C. Methane was desorbed from the catalyst at temperatures between 263 and 383°C which could be the explanation for the lower activity of the catalyst reduced at 170°C. It was demonstrated that small amounts of oxygen can have a beneficial effect in enantioselective hydrogenation of 1-phenyl-1,2-propanedione and also that catalyst reduction temperature plays an important role in obtaining high enantiomeric excesses.     

NiMo/HY催化剂上四氢萘加氢裂化反应网络与热力学平衡分析

采用固定床反应器对四氢萘在NiMo/HY工业催化剂上的加氢裂化反应过程进行了研究,考察了反应温度对产物分布的影响,提出了四氢萘加氢裂化反应网络。该网络包含加氢、异构、脱氢、开环、脱烷基等12个反应,通过热力学计算,得到了这些反应的平衡常数,并据此求得各类产物的平衡收率及其随温度、压力和氢气/四氢萘（摩尔比）的变化规律。由热力学平衡分析得到的产物收率随反应条件的变化规律与实验结果较为吻合,表明本文构建的反应网络可以较好地描述NiMo/HY催化剂上的四氢萘加氢裂化反应体系。     

对羧基苯甲醛在Pd/AC催化剂上加氢反应表观动力学

在实验室间歇高压釜中对Pd/AC催化剂上对苯二甲酸(TA)加氢精制过程的对羧基苯甲醛(4-CBA)加氢反应进行了研究。考察了氢分压、反应温度、催化剂颗粒大小对4-CBA消失速率的影响,并采用幂函数动力学模型拟合得到了接近工业反应温度范围的表观动力学方程。结果表明,氢分压0.35~1.0 MPa时,对4-CBA加氢反应的速率影响很小,反应速率对氢分压可视为零级,随着温度升高和催化剂颗粒减小,4-CBA加氢反应速率显著增加;工业条件下的TA加氢精制过程存在着严重的内外扩散,4-CBA加氢反应的表观活化能为28 kJ/mol,对4-CBA的反应级数为1.23。     

JT-8型加氢催化剂在焦炉煤气制甲醇装置上的工业应用

焦炉煤气制甲醇是一项具有明显经济效益、良好环境效益和社会效益的绿色可持续发展焦化技术工艺,焦炉煤气深度净化是关键技术。介绍JT-8型加氢催化剂在焦炉煤气制甲醇装置上的工业应用。工业应用结果表明,采用的JT-8型焦炉煤气加氢转化催化剂有机硫加氢转化率达98.1%、不饱和烃加氢饱和转化率达100%、O₂深度转化率达100%;二级脱硫反应器出口净化气中杂质含量和总硫含量完全满足后续工序＜0.1 mg·m^-3的要求,保证了生产装置长周期稳定运行。JT-8型加氢催化剂适应性强、深度转化能力高（有机硫加氢转化、不饱和烃加氢饱和及O²深度转化）、副反应少、性能稳定、处理量大和运行寿命长,具有明显的经济效益。     

Hydrogenation to products with IV below 1

The hydrogenation of fatty acids (FA) or fatty acid methyl esters (FAME) is a fundamental process to manufacture basic oleochemicals, like stabilizers and surfactants. These kinds of oleochemicals are used in downstream processes, to obtain products which are easily bio‐degradable, non‐irritant to the skin, and equipped with other favourable characteristics. In principle the FA or FAME are hydrogenated in a reactor under pressure, higher temperature and in the presence of a metallic catalyst, such as nickel or palladium. The process can be controlled in a desired direction by appropriate choice of these parameters to get a product with different degrees of saturation, melting properties and colour. The commonly used process nowadays is a batch process. The hydrogenation reaction is carried out in a loop or stirred reactor, in the presence of a suspended catalyst. After the reaction the catalyst must be removed from the product by an elaborate and time‐consuming filtration. This leads to higher consumption of catalyst. Another concern is that Ni‐soaps can be formed during the process leading to deactivation of catalyst and the presence of nickel in the final product. Therefore the fixed bed method was developed to eliminate these disadvantages. A pilot plant was constructed in which the catalyst is fixed on a carrier matrix and filled into the reactor and a test run was carried out with FA from tallow and FAME from palm oil. The iodine value of < 0.1 in hydrogenated FAME was achieved as required by the industry for the production of surfactants. In the fixed bed hydrogenation for ME nickel catalyst and for FA a palladium catalyst is used. Furthermore catalyst is reused, its consumption is reduced and the formation of byproducts is minimized. The process is characterized by a high reliability, feed flexibility, easy control and high yield.     

Selective hydrogenation of sunflower seed oil in a three-phase catalytic membrane reactor

Continuous hydrogenation of sunflower seed oil has been carried out in a novel three-phase catalytic membrane hydrogenation reactor. The membrane reactor consisted of a membrane impregnated with Pd as the active catalyst, which provided a catalytic interface between the gas phase (H₂) and the oil. Hydrogenations were carried out at different pressures, temperatures, and selectivities, and the formation of trans isomers was monitored during the hydrogenation runs. For the three-phase catalytic membrane reactor, interfacial transport resistances and intraparticle diffusion limitations did not influence the hydrogenation reaction. Hydrogenation runs under kinetically controlled conditions showed that oleic and elaidic acid were not hydrogenated in the presence of linoleic acid. Initial formation of stearic acid was caused by direct conversion of linoleic acid into stearic acid by a shunt reaction. Furthermore, high selectivities led to high trans levels, which is in accordance with the many published data on hydrogenation of vegetable oils in slurry reactors. Finally, the catalytic membrane showed severe catalyst deactivation. Only partial recovery of the catalyst activity was possible.     

Selective Hydrogenation of 1‐Butene Rich Cuts: the Impact of the Intraparticle Diffusion Limitations on the Selectivity

The impact of intraparticle diffusion limitations on the selectivity of an industrial reactor for selective hydrogenation of 1‐butyne and 1,3‐butadiene contained in 1‐butene rich cuts was evaluated. To this end, a simple model of a trickle‐bed reactor was employed and actual process operating conditions were chosen. A kinetic model was chosen whose parameters correspond to a commercial catalyst. These parameters were calculated from experiments conducted under industrial operating conditions. The complex diffusion and reaction phenomena occurring inside catalyst pellets placed at different depths of the reactor are comprehensively described. 1‐Butene losses in the range 20–30 %, which are usual in commercial plants, were predicted. It was concluded that the operating pressure is crucial for enhancing process selectivity.     

Hydrogenation of acetophenone using a 10% Ni supported on zeolite Y catalyst: kinetics and reaction mechanism

The kinetics of hydrogenation of acetophenone was studied using a 10% Ni supported on zeolite Y catalyst in a temperature range 353–393 K. The effect of H₂ pressure, initial concentration of acetophenone and catalyst loading on the concentration-time profiles was studied. Water formed during the course of hydrogenation showed a strong inhibiting influence on the rate of reaction. A rate equation has been proposed based on L–H type rate mechanism assuming that the reaction between the non-competitively adsorbed hydrogen and the adsorbed organic substrate as rate limiting step. A semi-batch reactor model was developed to predict the concentration-time, H₂ consumption-time profiles at different sets of initial conditions. The model predictions were found to agree with experimental data very well at all temperatures. This model incorporates the inhibition of hydrogenation rate due to water. The inhibiting effect of water is also explained based on quantum chemical calculations.     

Heterogeneous enantioselective hydrogenation of isophorone over proline modified Pd catalysts

Enantioselective hydrogenation of isophorone (3,5,5-trimethyl-2-cyclohexenone) over (S)-proline modified Pd catalysts has been studied. Both the Pd particle size and the acid–base properties of the support influenced the hydrogenation reaction of isophorone and the subsequent kinetic resolution of 3,3,5-trimethylcyclohexanone (TMCH). This was explained by assuming the reaction pathway as a consequential process. The rapid hydrogenation of isophorone initially yielded racemic TMCH, and then the slow kinetic resolution consumed the (R)-TMCH, leaving (S)-TMCH in excess. Most promisingly, the Pd/MgO catalyst with enhanced adsorption of proline and moderate Pd particle sizes resulted in high enantioselectivity (ee of 95%) and 43% yield of TMCH.     

以单质硫为硫化介质的加氢催化剂间歇釜器外预硫化工艺

利用间歇釜研究了以单质硫为硫化介质, 对一种Co-Mo-Ni/Al₂O₃加氢催化剂进行器外预硫化时, 硫和氢气配比、硫用量、初始反应温度及时间、硫化终温和时间等工艺条件对硫化效果的影响, 并对不同状态催化剂进行了XRD、SEM及BET的分析表征。以硫化度作为硫化效果评价指标, 确定优化的硫化条件:硫为1.2倍理论消耗量, 硫和氢气摩尔配比1:3, 低温硫化和高温硫化温度分别为160℃和320℃, 两段恒温硫化时间分别为3h和2h。对硫化后的催化剂进行了真实原料的加氢活性评价, 实验结果表明, 以单质硫作为硫化介质, 利用歇釜可满足器外预硫化的需求, 与器内硫化相比, 硫化度和加氢活性等具有明显优势。     

中低温煤焦油加氢转化路径

以中低温煤焦油360℃的馏分油为原料,Ni-Mo/γ-Al2O3为催化剂,在小型固定床单管加氢反应器上进行加氢实验。在压力13 MPa、空速0.4 h-1、氢油体积比1 700∶1和反应温度370℃工艺条件下进行催化加氢反应,通过对原料油和加氢产物的GC-MS的检测结果分析,确定了酚类、萘类、联苯类和菲类化合物的加氢转化路径,得到煤焦油馏分油中主要化合物的加氢反应网络。     

Similar effect of carbon and silica catalyst support on the hydrogenation reaction rate in organic slurry reactors

This paper investigates the influence of the catalyst support type on mass transport and reaction rate for the case of hydrogenation of α-methylstyrene to cumene in a gas inducing stirred slurry reactor and in a slurry bubble column. The reaction is carried out in the presence of 3% Pd/carbon and 3% Pd/silica catalyst particles. The lyophobicity of the two catalyst supports in the cumene slurry is found to be similar. The overall rate of the hydrogenation reaction is described by the classical transport and reaction resistances-in-series model. The rate of gas-to-liquid mass transfer is somewhat larger during reaction than without reaction. This enhanced mass transfer points to particle-to-bubble adhesion as a result of the relative affinity of both catalyst supports to the gas phase. The observed reaction enhancements are similar for both Pd/carbon and Pd/silica catalyst/cumene slurries.     

Effect of phase maldistribution on performance of two-phase catalytic monolith reactor and its comparison with trickle bed reactor

Monolith reactors are widely considered as an alternative to the conventional trickle bed reactor. For the commercial deployment of monolith reactors, comparative performance studies are required. Reliable comparative and performance studies require a detailed understanding of the effect of phase distribution/maldistribution on the performance studies. In this work, performance and comparative studies were carried out in a relatively large column that was 4.8 cm in diameter. Experiments were performed in the same conditions that were used in studies for which phase distribution data were available. Since the properties of the catalyst used were different in both the reactors, the apparent kinetics were studied to facilitate the comparison. The hydrogenation of alpha-methyl styrene (AMS) was used as a test reaction. From the performance studies, it was found that the effect of maldistribution on the performance was stronger than the catalyst availability. From the comparative studies, it was found that the monolith reactor with maldistributed flow conditions provides higher productivity than the trickle bed reactor.     

Enantioselective hydrogenation of isophorone and kinetic resolution of 3,3,5-trimethylcyclohexanone over Pd catalysts in the presence of (S)-proline

Enantioselective hydrogenation of isophorone and kinetic resolution of 3,3,5-trimethylcyclohexanone (TMCH) over Pd catalysts in the presence of (S)-proline revealed that the enantioselectivity for hydrogenation of isophorone was mainly originated from the kinetic resolution of TMCH. The rapid hydrogenation of isophorone primarily yielded racemic TMCH, and the followed kinetic resolution consumed the (R)-TMCH enantiomer, leaving the (S)-TMCH enantiomer in excess. The kinetic resolution of racemic TMCH is closely related to the acidic/basic properties of the support, and the addition of K₂CO₃ to Al₂O₃ provided more enantio-differentiating environment through the enhanced adsorption of (S)-proline on the catalyst surface. As a result, the Pd/Al₂O₃-K₂CO₃ catalyst with finely dispersed Pd particles and enhanced adsorption of (S)-proline gave very high enantioselectivities (e.e. value up to 98%) for the enantioselective hydrogenation of isophorone.     

不同二异氰酸酯三聚反应分子模拟与反应动力学研究

利用DMol3分子模拟软件对二苯基甲烷二异氰酸酯(MDI)、氢化二苯基甲烷二异氰酸酯(HMDI)、异佛尔酮二异氰酸酯(IPDI)3种异氰酸酯自聚反应进行了模拟计算;利用傅里叶变换红外光谱(FT-IR)对不同异氰酸酯在催化剂2,4,6-三(二甲胺基甲基)苯酚(DMP-30)作用下的三聚反应进行了跟踪,研究了不同催化剂用量、反应温度、反应时间下3种异氰酸酯的自聚反应动力学。结果表明,异氰酸酯自聚反应倾向生成稳定的六元环结构;3种异氰酸酯三聚反应均为二级反应,MDI在加入催化剂质量分数0.05%时,反应的活化能为26.1 kJ/mol,IPDI和HMDI在加入催化剂质量分数2%时,反应的活化能分别为13.5 kJ/mol和49.9 kJ/mol。     

Kinetic investigations of the deactivation by coking of a noble metal catalyst in the catalytic hydrogenation of nitrobenzene using a catalytic wall reactor

The vapour phase hydrogenation of nitrobenzene to aniline is a highly exothermic reaction deactivated by coking of the palladium catalyst supported on -alumina carrier. For studying the deactivation of the catalyst a catalytic wall reactor was used in order to ensure isothermal reaction conditions for the kinetic measurements. Furthermore, the catalytic wall reactor allowed the determination of axial coke profiles by total carbon analysis of different wall segments. On the assumption that the main reaction and the deactivation of the catalyst can be assumed separable both the steady state and the unsteady state kinetics were studied. Nitrobenzene was identified as the relevant coke precursor whereas aniline has neither an influence on the main reaction nor on the deactivation. It could be shown that the hydrogenation of nitrobenzene to aniline follows a Langmuir–Hinshelwood mechanism considering the surface reaction of the adsorbed nitrobenzene molecule and one adsorbed hydrogen atom as the rate determining step. The differentiation of coke on the active sites and coke on the support must be taken into account to model the kinetics of coke formation with sufficient accuracy.     

异氟尔酮在蛋壳型Pd/Al2O3催化剂上的选择性加氢

采用等体积浸渍法制备出蛋壳型Pd/Al2O3催化剂,采用连续加氢固定床微反装置研究了异佛尔酮(IP)的选择性加氢反应,考察了载体焙烧温度、蛋壳层厚度、Pd负载量及粒子大小、溶剂等反应条件对Pd/Al2O3催化剂上IP选择性加氢的影响.结果表明,蛋壳型Pd/Al2O3是IP选择性加氢制备3,3,5-三甲基环己酮(TMCH)的优异催化剂,反应条件缓和,IP转化率及TMCH选择性均可达到99.5％以上,具有良好的工业应用前景.     

镁铝复合氧化物制备及其 丙酮缩聚制异佛尔酮反应研究

采用共沉淀法制备了一系列不同镁铝比的镁铝复合氧化物催化剂,通过XRD、BET和Py-IR等分析手段对催化剂进行了分析,并在连续流动常压固定床微反装置上研究了镁铝复合氧化物催化剂对丙酮气相缩聚制异佛尔酮反应的催化性能。结果表明,共沉淀法制得的镁铝复合氧化物催化剂具有较高的比表面积、较大的平均孔径和孔容,其中MA35催化剂是性能最好的镁铝复合氧化物催化剂,在反应温度为250 ℃、空速为1 h-1、压力为0.1 MPa的条件下,催化剂对丙酮气相缩聚反应的单程转化率为18.8%,异佛尔酮选择性为46.5%。     

Hydrodesulphurization of thiophene by coal mineral matter and a cobalt-molybdate catalyst in a pulse reactor

A pulse reactor was used to compare the catalytic activity of a commercial desulphurization catalyst (Nalco 471) and of mineral matter from Western Kentucky coal. Hydrodesulphurization of thiophene, a model coal sulphur compound, was the reaction studied. Mineral matter was obtained from the coal in its least altered state by a low-temperature, oxygen-plasma technique commonly referred to as low-temperature ashing. Conversion is determined from the C₄ gases which are separated in a two-column Chromatographic system. At 748 K it was found that thiophene conversion with mineral matter was 12% of that with the commercial catalyst. Relative activities of hydrogenation of intermediate butenes to butane, the effect of presulphiding, and that of pyridine poisoning were also determined.