Complete carbon analysis of sulfur‐containing mixtures using postcolumn reaction and flame ionization detection

Quantitative analysis of complex mixtures containing hundreds‐to‐thousands of organic compounds rich in heteroatoms, including oxygen, sulfur, and nitrogen, is a major challenge in the fuel, food, and chemical industries. In this work, a two‐stage (oxidation and methanation) catalytic process in a 3‐D–printed metal microreactor was evaluated for its capability to convert sulfur‐containing organic compounds to methane. The microreactor was inserted into a gas chromatograph between the capillary column and flame ionization detector. Catalytic conversion of all sulfur‐containing analytes to methane enabled carbon quantification without calibration, by the method identified as “quantitative carbon detection” or QCD. Quantification of tetrahydrothiophene, dimethyl sulfoxide, diethyl sulfide, and thiophene indicated complete conversion to methane at 450°C. Long‐term performance of a commercial microreactor was evaluated for 2000 consecutive injections of sulfur‐containing organic analytes. The sulfur processing capacity of the microreactor was identified experimentally, after which reduced conversion to methane was observed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5438–5444, 2017     

Novel hierarchical Ni/MgO catalyst for highly efficient CO methanation in a fluidized bed reactor

A facile synthesis of the hierarchical Ni/MgO catalyst is reported, with extremely fine dispersion of Ni nanoparticles (NPs) and high surface oxygen mobility. The hierarchical Ni/MgO catalyst exhibits higher activity for CH₄ formation than that prepared by the impregnation method. The enhanced activity and thermal stability of the hierarchical Ni/MgO catalyst is attributed to hierarchical MgO particles with a multilayer structure and high surface oxygen mobility. This induces better metal‐support interactions, high Ni dispersion to prevent Ni NPs sintering, and the high surface oxygen mobility provides a high resistance to carbon deposition. Compared to the impregnated Ni/MgO catalyst, the hierarchical Ni/MgO catalyst exhibits a better fluidization quality and a higher attrition‐resistance in a fluidized‐bed reactor. This approach to improve the catalytic activity by creation of hierarchical Ni/MgO particles is encouraging for the design of novel catalysts for synthetic natural gas production, especially from the perspective of matching catalysts with fluidized‐bed reactors. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2141–2152, 2017     

等高压甲醇甲烷化技术的应用

概述了等高压甲醇甲烷化技术在浙江江山化工股份公司的应用情况。实际运行证明，等高压甲醇甲烷化取代传统的铜洗工艺，完全可以满足合成氨对原料气精制的要求，而且具有良好的经济效益。     

Preferential CO Oxidation in the Presence of H2, H2O and CO2 at Short Contact-times

High selectivities and conversions in the preferential oxidation of CO in the presence of large quantities of H₂, H₂O and CO₂ are demonstrated on noble metal catalysts at millisecond contact times (~10–15 ms) for temperatures between 150 and 500 °C. With a simulated water-gas shift product stream containing 0.5% CO and varying amounts of H₂, H₂O and CO₂, we are able to achieve ~90% CO conversions on a Ru catalyst at temperatures of ~300 °C using a stoichiometric amount of O₂ (0.25%). Experiments with and without O₂ and with varying H₂O reveal that significant water-gas shift occurs on Pt and Pt-ceria catalysts at temperatures between 250 and 400 °C, while significant CH₄ is formed on Ru and Rh catalysts at temperatures greater than 250 and 350 °C, respectively. The presence of H₂O blocks H₂ adsorption and allows preferential CO oxidation at higher temperatures where rates are high. We propose that a multistage preferential oxidation reactor using these catalysts can be used to bring down CO content from 5000 ppm at the reactor entrance to less than 100 ppm at very short contact-times.     

煤制气托普索甲烷化工艺热力学分析

利用化工流程模拟软件Aspen Plus,对煤制气托普索甲烷化工艺第一级带循环回路的反应系统进行了模拟研究。考察了在恒温条件下,反应器的温度、压力、循环比、水蒸气比对反应器出口甲烷含量和热负荷的影响:在绝热条件下,反应器的压力、循环比、水蒸气比对反应器出口温度和甲烷含量的影响。结果表明,在恒温条件下,除循环比外各因素对甲烷平衡含量都有影响,其中温度影响较大,温度越高,甲烷平衡含量越小;在绝热条件下,各因素对反应器出口温度和甲烷平衡含量都有影响,其中循环比影响较大,循环比越大,反应器出口温度越低,甲烷平衡含量越大,通过虚拟正交实验研究,得到各因素对反应器出口温度和甲烷含量的影响大小顺序为:循环比水蒸气比压力。     

Evidence for anchoring and partial occlusion of metallic clusters on the pore walls of MCM-41 and effect on the stability of the metallic clusters

In order to explain the high stability of the Co- and Ni-MCM-41 catalysts, the hypotheses of anchoring of small metallic clusters to cations in and partial occlusion of the metallic clusters by amorphous silica are proposed. Carbon monoxide chemisorption on model catalysts and Co-MCM-41 has given direct proof of the metal anchoring effect on the stability of metal cluster dispersion. The partial occlusion of metallic clusters, which may lead to physical confinement (inhibited migration) or chemical confinement (inhibited reaction), was monitored by CO in situ FTIR and CO methanation along with a kinetic study, which confirmed that the metallic clusters on the pore surface result in the stabilization of the catalysts against deactivation. A fine tuning of these physicochemical phenomena in the transition metal incorporated MCM-41 will make possible the design of stable catalytic systems for reactions requiring metallic active sites under severe reaction conditions.     

国外甲烷化技术发展现状

对国外现有甲烷化技术进行综述性评价的基础上,分析、比较了Davy、TREMPTM、Lurgi 3种技术的工艺流程、技术特点,根据煤制天然气生产特点,对甲烷化技术的发展提出了建议。     

流化床甲烷化反应动力学模拟

利用AspenPlus结合Fortran编写的动力学子程序对流化床甲烷化反应进行建模，结果显示该模型与实验值吻合较好。基于该模型考察了不同工艺条件对cH4收率影响，研究表明：随着反应温度升高，CH4收率逐渐降低，压力越小，cH4收率下降越明显；原料气流量对甲烷化反应影响较小，增加流量，CH4收率呈现降低趋势；当氢碳比在2．7—3．0范围内，CH4收率增幅较大，氢碳比大于3．0时，CH4收率增加缓慢。     

颗粒尺度下混合催化剂床层中CO2加氢反应体系数值模拟

CO2的有效转化对于实现“双碳”目标具有重要意义。柱形颗粒比异形颗粒具有更优良的热导性和更小的颗粒表面积,因此,为获得更优异的床层性能,采用离散元方法(DEM)对异形颗粒混合堆积床内的CO2加氢反应体系进行颗粒尺度CFD模拟计算,探究不同堆积方式对床层多物理场分布、CO2转化率及CH4产率的影响。结果表明,催化剂内部存在扩散阻力,随着反应进行,颗粒内物质由分层分布渐变为均匀分布。随机混合床与常规床相比,随机混合床稳态前热点不易波动、稳态产率更高,而柱形床径向热场更均匀且热点更高。在四种规则混合床中,底部为4孔的两种催化剂床相较于底部为柱形的两种催化剂床,整体流场更均匀、高速区少、压降大、高温区占比大、稳态前热点不易波动;2层-底4孔催化剂床的稳态出口CO2转化率和CH4产率均最大;4层-底4孔催化剂床高温区占比较高,随着反应进行,高温区占比呈上升趋势,CO2转化率和CH4产率大幅下降。     

Dynamic analysis on methanation reactor using a double-input-multi-output linearized model☆

A double-input–multi-output linearized system is developed using the state-space method for dynamic analysis of methanation process of coke oven gas. The stability of reactor alone and reactor with fee...