B112催化剂上一氧化碳变换反应工业过程动力学研究

采用“沿程积分拟合法”,在某小合成氨厂变换工段引出的支线上,利用绝热固定床反应器,对B112催化剂上一氧化碳变换反应进行了常压及加压工业过程的动力学研究。通过对不同操作条件下的床层轴向温度分布进行积分拟合,得到了适用于工业条件的过程动力学方程。一氧化碳变换反应 CO+H_2~O(?)CO_2+H_2 是石油化工和煤化工重要的化学反应。国内外学者对许多种铁系催化剂上的该反应进行了动力学研究,推荐了各自的本征或宏观动力学方程。本文采用“沿程积分拟合法”对国产B112催化剂上的一氧化碳变换反应进行工业过程动力学研究。按照该法的要求,实验中需采用与工业实际反应器(绝热固定床反应器)型式相同的小型反应器,在工业条件下,测定不同进口条件的反应器轴向温度分布及出口浓度,通过积分拟合获得工业过程动力学方程。     

B112催化剂上一氧化碳变换反应工业过程动务学研究

采用“沿程积分拟合法”，在某小合成氨厂变换工段引出的支线上，利用绝热固定床反应器，对B112催化剂上一氧化碳变换反应进行了常压及加压工业过程的动力学研究。通过对不同操作条件下的床层轴向温度分布进行积分拟合，得到了适用于工业条件的过程动力学方程。一氧化碳变换反应CO＋H2O＝CO2＋H2是石油化工和煤化工重要的化学反应。国内外学者以地许多种铁系催化剂上的该反应进行了动力学研究^[1-5]，推荐了各自的本征或宏观动力学方程。本文采用“沿程积分拟合法”^[6]对国产B112催化剂上的一氧化碳变换反应进行工业过程动力学研究。按照该法的要求，实验中需采用与工业实际反应器（绝热固定床反应器）型式相同的小型反应器，在工业条件下，测定不同进口条件的反应器轴向温度分布及出口浓度，通过积分拟合获得工业过程动力学方程。     

低汽/气LB型中温变换催化剂宏观动力学

采用磁力搅拌内循环无梯度反应器,对低汽/气LB型一氧化碳中温变换催化剂的宏观反应特性进行了实验研究?并以Simplex法对实验数据进行非线性参数估值,建立了能良好吻合实验数据的二级反应模式的LB中温变换催化剂加压宏观动力学模型。     

多孔催化剂效率因子的多组分扩散模型 (Ⅱ)B109中温变换催化剂的效率因子

按照本文(Ⅰ)中提出的多孔催化剂效率因子的多组分扩散模型及其数值计算方法,本报计算了B109中温变换催化剂的效率因子,并与实验测定值进行了比较.测试了B109变换催化剂的孔隙率、孔径分布、曲节因子和常压下的本征动力学,并在内循环无梯度反应器中测试了常压下φ9.8×8.3mm圆柱状颗粒B109催化剂于各种气体组成和温度条件下只计入内扩散过程的宏观反应速率.由此获得十六种情况下效率因子的实验观察值为0.142至0.455,相同反应条件下模型预计值与实验观察值的相对误差为-0.25至0.06.比较的结果令人满意.     

多孔催化剂效率因子的多组分扩散模型(Ⅲ)——加压下WB-2中温变换催化剂的效率因子

在内循环无梯度反应器中研究37×10~5Pa(表)及13×10~5Pa(表)压力下工业粒度ф9×7mm.WB-2中温变换催化剂的宏观反应速率,测试了催化剂的孔径分布和曲节因子.本报应用常压下测得的本征动力学方程,对于十七组宏观实验速率,按照前报(Ⅱ)提出的简化多组分扩散模型,求取了效率因子的数值解,并与实验观察值作了比较.比较的结果令人满意.本报由此认为,对于中温变换这类压力不高的反应,研究其加压宏观动力学行为,不必进行加压宏观速率的实验测定.加压下的效率因子及宏观反应速率可在常压测得的本征动力学基础上借助本文提出的模型计算求得.     

应用内循环无梯度反应器进行常压下变换反应宏观动力学研究

为实现工业变换反应器设计的模拟放大及设计、操作的最佳化,本文在研究中温变换B_(109)型催化剂本征动力学的基础上,采用内循环无梯度反应器,对工业原粒度中温变换B_(109)型催化剂在常压下进行了宏观动力学的研究,即对催化反应的内扩散过程进行深入研究。并运用电子计算技术,对实验数据进行回归整理,得到了宏观动力学经验方程,经工业变换炉核算,该宏观动力学方程具有良好的等效性。     

球形钻相变换催化剂宏观活性评价方法

本文以B303Q型钻钥耐硫变换催化剂为例,研究了有关反应器材质、活性评价基准以及颗粒直径的影响。认为以二级反应速率常数作为催化剂宏观特性,不受反应组成的影响,并具有计算过程简捷的优点。求得了不同粒径的反应速率常数之 比以及同颗粒直径和温度的关系式。     

QCS—04催化剂3.0MPa宏观反应动力学研究

采用内循环无梯度反应器,对工业原粒度ＱＣＳ－０４耐硫变换催化剂在３．０ＭＰａ下的宏观动力学进行了研究,测定３００～４８０℃温度范围内,不同组成原料气的变换反应速率。用非线性最小二乘法求得了变换反应幂函数型的宏观动力学方程。显著性检验及对工业变换反应器模拟的结果证明所得方程是可靠的。     

绝热固定床反应器的乙醇脱水制乙烯反应工艺

为开发新型生物质乙醇脱水制乙烯反应工艺,采用了上海石油化工研究院开发的氧化铝催化剂,在绝热床反应器中进行了工艺实验优化研究。考察了不同水醇质量比、空速和反应器进口温度等对乙醇转化率和乙烯选择性的影响,应用该实验数据,结合前期建立的该催化剂上的乙醇脱水催化反应本征动力学,对该催化剂上的乙醇脱水催化反应本征动力学方程系数进行校正,计算出关于关键组分的该催化剂的效率因子,建立了更适宜于工业应用的宏观动力学模型,模型计算结果与实验数据吻合较好。相对于等温固定床反应工艺或单段绝热床反应工艺,所研发的氧化铝催化剂上四段绝热床反应工艺的能耗降低,乙醇转化率提高,乙烯选择性得到很大的提高,为工业反应器的优化设计以及放大提供必须的工艺设计数据。     

环氧乙烷非均相催化水合动力学及均温反应器热稳定性分析

采用碳纳米管增强复合材料催化剂,在等温积分反应器中获得环氧乙烷非均相催化水合宏观反应动力学实验数据,建立了幂函数型宏观反应动力学方程,采用Levenberg-Marquardt法对动力学模型参数进行估算,并以该动力学模型为基础,分析了均温反应器的热稳定性。结果表明,生成乙二醇主反应的表观活化能为71.7 k J/mol,与两个典型的串联副反应的活化能接近。模型参数统计检验结果表明,该宏观动力学方程参数是适定的,可用于工业反应器的设计。给出的反应器关键参数的计算方法,可为乙二醇合成反应器的模拟计算和设计开发提供必要的依据。     

Study of the Suitability of a Pt-Based Catalyst for the Upgrading of a Biomass Gasification Syngas Stream via the WGS Reaction

In this article, the catalytic activity of a Pt-based water gas shift (WGS) catalyst is presented. The experimental study has been conducted under realistic conditions typical of pressurised oxygen gasification. The effect of temperature, space velocity, steam to carbon monoxide ratio, and gas composition on the performance of the catalyst is investigated. Despite the high CO content in the feed gas, ranging from 32% to 60% v/v, dry basis, the catalyst has shown very good performance at intermediate temperature, 300–450 °C. Carbon monoxide concentration at the reactor outlet reached values below 3% what is comparable with conventional high-temperature, first-stage WGS catalysts.     

Hydrogen production by the catalytic steam reforming of methanol: Part 3: Kinetics of methanol decomposition using C18HC catalyst

The rate of catalytic decomposition of methanol in the presence of steam has been studied using a commercial CuO-ZnO-Al₂O₃. low temperature shift catalyst from 150-270°C at one atmosphere pressure in a fixed bed reactor. Mole ratios of steam to methanol of 0.66. 1.0 and 1.5 and catalyst mass to molar feed rate ratios of 25 to 1025 kg. s. mol ^?1 were utilized. The data were correlated and equations developed to successfully predict methanol conversions and carbon monoxide concentrations in the product gas stream over the temperature range studied. No evidence of mass transfer limitations was observed.     

Some effects of carbon monoxide in hydroprocessing of heavy feedstocks

Hydroprocessing routes, when utilized for upgrading bituminous feedstocks and heavy oils, represent versatile means for production of additional liquid fuels. Production of pure hydrogen involves expensive gas purification and shift conversion steps so that by-passing these would be economically beneficial. Experiments undertaken to determine the effect of the presence of carbon monoxide (CO) in the hydrogen stream on the hydrocracking of Athabasca bitumen in a high-pressure continuous-flow system showed that CO content up to 50 mol % in the hydrogen feed would not affect thermal hydrocracking detrimentally. The use of a catalyst with stabilizing capability emphasized the apparent non-interference of CO with thermal cracking. On the other hand, significant performance inhibition of molybdenum-containing multi-functional catalysts indicated surface poisoning by CO adsorption which was partially alleviated in the presence of steam. On the addition of water to the feedstock, the latter catalysts caused substantial water-gas shift reaction to take place, accompanied by less extensive methanation. These reactions were less apparent with the other type of catalysts. Depending upon feedstock characteristics it may be possible to incorporate catalytic components allowing the presence of CO in the feed. In the overall evaluation, other important effects of CO presence would have to be examined in connection with the coking propensity of the feedstock and the reactor temperature control.     

碱金属助剂对铜系低变催化剂低汽气比条件下稳定性和选择性的影响

采用原粒度催化反应装置,结合物理分析化学手段,研究了添加碱金属助剂对铜系低变催化剂在低汽气比条件下稳定性和选择性的影响。发现添加一定量的某种碱金属氧化物助剂,可以减少低汽气比条件下铜系低变催化剂的甲醇生成量。在一定的添加量范围内,其变换反应性能稳定,并且甲醇副产物的生成量也较稳定,但碱金属助剂的添加对催化剂的比表面积和强度的影响较大。     

新型铜系低变催化剂在低汽气比条件下的性能研究

采用原粒度催化反应装置,结合物理分析和化学手段,研究添加碱金属助剂对铜系低变催化剂在低汽气比条件下稳定性的影响。发现添加适量的碱金属氧化物助剂可以减少低汽气比条件下铜系低变催化剂的甲醇生成量,一定的添加量范围内,变换反应性能和甲醇副产物的生成量较稳定,但碱金属助剂的添加对催化剂的比表面积和强度的影响较大。     

PEM – Fuel Cell System for Residential Applications

Viessmann is developing a PEM fuel cell system for residential applications. The uncharged PEM fuel cell system has a 2 kW electrical and 3 kW thermal power output. The Viessmann Fuel Processor is characterized by a steam‐reformer/burner combination in which the burner supplies the required heat to the steam reformer unit and the burner exhaust gas is used to heat water. Natural gas is used as fuel, which is fed into the reforming reactor after passing an integrated desulphurisation unit. The low temperature (600 °C) fuel processor is designed on the basis of steam reforming technology. For carbon monoxide removal, a single shift reactor and selective methanisation is used with noble metal catalysts on monoliths. In the shift reactor, carbon monoxide is converted into hydrogen by the water gas shift reaction. The low level of carbon monoxide at the outlet of the shift reactor is further reduced, to approximately 20 ppm, downstream in the methanisation reactor, to meet PEM fuel cell requirements. Since both catalysts work at the same temperature (240 °C), there is no requirement for an additional heat exchanger in the fuel processor. Start up time is less than 30 min. In addition, Viessmann has developed a 2 kW class PEFC stack, without humidification. Reformate and dry air are fed straight to the stack. Due to the dry operation, water produced by the cell reaction rapidly diffuses through the electrolyte membrane. This was achieved by optimising the MEA, the gas flow pattern and the operating conditions. The cathode is operated by an air blower.     

The activity of commercial water gas shift catalysts

Published kinetic data for commercial water gas shift catalysts are interpreted in terms of pore diffusional effects. The Arrhenius plots of apparent activity show the curvature typical of the transition from reaction to pore diffusion control and the apparent activities of different catalyst pellets vary quite widely. Effective diffusivity data are used to calculate intrinsic rate constants from the apparent activity data and it is found that the intrinsic activities of the catalysts considered are all similar. Furthermore the intrinsic activities, calculated in this way, give linear Arrhenius plots and activation energies which are in good agreement with values obtained experimentally using small catalyst particles (22–27 K. Cals). The effect of pressure on apparent catalyst activity is also discussed and it is shown that this effect may be accounted for satisfactorily by pore diffusional effects and it is not necessary to assume a change in the intrinsic rate equation at least at pressures below 20 atms.     

一氧化碳低温变换催化剂研究进展

介绍了一氧化碳催化剂的研究情况和发展方向。对比了铁系高温变换催化剂、铜系低温变换催化剂、钴钼系耐硫宽温变换催化剂以及二氧化铈基水煤气变换催化剂的使用条件;阐述了上述催化剂的工业应用前景。     

Catalytic steam reforming of chlorocarbons: polychlorinated biphenyls (PCBs)

Experiments with commercial askarals (Aroclors 1221, 1248 and 1254) have confirmed the feasibility of catalytic steam reforming as a method for destroying polychlorinated biphenyls (PCBs). Rhodium, platinum and nickel supported on γ-Al₂O₃ were used as catalysts. Process conditions were GHSV=10 000–17 000 h⁻¹; H₂O/C=10; and temperature=400–700°C. The Ni catalyst was the most active, giving conversions of 0.9999+ and stable operation at temperatures as low as 400°C. A slight amount of deactivation due to carbon formation was apparent at longer process times. This increased with the degree of chlorination of the PCBs. Carbon monoxide was the dominant carbon product, increasing with time due to poisoning of the water gas shift reaction by chloride species. Platinum achieved essentially the same results, except that higher temperatures (600°C) were necessary and deactivation occurred sooner. Examination of trace amounts of unconverted PCBs indicated a progressive dechlorination of the biphenyl ring.     

Steam reforming of ethanol over skeletal Ni‐based catalysts: A temperature programmed desorption and kinetic study

An investigation on reaction scheme and kinetics for ethanol steam reforming on skeletal nickel catalysts is described. Catalytic activity of skeletal nickel catalyst for low‐temperature steam reforming has been studied in detail, and the reasons for its high reactivity for H₂ production are attained by probe reactions. Higher activity of water gas shift reaction and methanation contributes to the low CO selectivity. Cu and Pt addition can promote WGSR and suppress methanation, and, thus, improve H₂ production. A reaction scheme on skeletal nickel catalyst has been proposed through temperature programmed reaction spectroscopy experiments. An Eley‐Rideal model is put forward for kinetic studies, which contains three surface reactions: ethanol decomposition, water gas shift reaction, and methane steam reforming reaction. The kinetics was studied at 300–400°C using a randomized algorithms method and a least‐squares method to solve the differential equations and fit the experimental data; the goodness of fit obtained with this model is above 0.95. The activation energies for the ethanol decomposition, methane steam reforming, and water gas shift reaction are 187.7 kJ/mol, 138.5 kJ/mol and 52.8 kJ/mol, respectively. Thus, ethanol decomposition was determined to be the rate determining reaction of ethanol steam reforming on skeletal nickel catalysts. © 2013 American Institute of Chemical Engineers AIChE J 60: 635–644, 2014