Rational Design of FeNi Bimetal Modified Covalent Organic Frameworks for Photoconversion of Anthropogenic CO2 into Widely Tunable Syngas

Direct photoconversion of low‐concentration CO₂ into a widely tunable syngas (i.e., CO/H₂ mixture) provides a feasible outlet for the high value‐added utilization of anthropogenic CO₂. However, in the low‐concentration CO₂ photoreduction system, it remains a huge challenge to screen appropriate catalysts for efficient CO and H₂ production, respectively, and provide a facile parameter to tune the CO/H₂ ratio in a wide range. Herein, by engineering the metal sites on the covalent organic frameworks matrix, low‐concentration CO₂ can be efficiently photoconverted into tunable syngas, whose CO/H₂ ratio (1:19–9:1) is obviously wider than reported systems. Experiments and density functional theory calculations indicate that Fe sites serve as the H₂ evolution sites due to the much stronger binding affinity to H₂O, while Ni sites act as the CO production sites for the higher affinity to CO₂. Notably, the widely tunable syngas can also be produced over other Fe/Ni‐based bimetal catalysts, regardless of their structures and supporting materials, confirming the significant role of the metal sites in regulating the selectivity of CO₂ photoreduction and providing a modular design strategy for syngas production.     

Segregation of Pt and Re During CO2 Reforming of CH4

Pt–Re supported on Ce_0.52 Zr_0.48 O₂ was studied for the carbon dioxide reforming of methane at 800 °C. Diffuse reflectance fourier transform infrared spectroscopy and temperature programmed reduction studies suggest that Pt and Re segregation occurs during the reaction. The segregation results in an increase in the Pt sites available for CH₄ decomposition and results in the bimetallic catalyst exhibiting an increase in the conversion of methane with time on stream. After 20 h of reaction, the CH₄ conversion observed for the bimetallic catalyst was the same as the CH₄ conversion observed for the monometallic catalyst.     

水蒸气/氧流化床两段煤气化制备低焦油合成气工艺实验

由下行床热解和提升管（或输送床）气化组合形成的流化床两段气化将煤气化反应过程解耦为煤热解和半焦气化两个反应阶段,热解产物完全进入气化反应器,利用其中的高温环境和输送的半焦催化作用分别实现焦油的热裂解与催化裂解,完成低焦油气化。利用该流化床两段气化的10 kg/h级实验室工艺实验装置,以榆林烟煤为原料、水蒸气/氧气作为气化剂,变化过量氧气系数ER、蒸汽炭比S/C、热解及气化温度等参数,研究水蒸气/氧流化床两段煤气化制备低焦油合成气的特性。结果表明,流化床两段气化系统可实现稳定运行（实验3 h以上）,在ER=0.36和S/C=0.15时,热解和气化的代表温度分别稳定在735℃和877℃,合成气的CO、CO₂、H₂、CH₄、C _n H _m 和N₂含量分别为14.33%、10.07%、18.39%、9.89%、1.82%和45.50%,相应的合成气产量达到1.8 m³/kg,低位热值8.99 MJ/m³,焦油含量0.437 g/m³,展示了制备低焦油合成气的技术特征。对于实际的长时间连续运行,更高的气化温度将使流化床两段气化具有更好的低焦油特性。     

Novel and Ideal Zirconium-Based Dense Membrane Reactors for Partial Oxidation of Methane to Syngas

A novel and ideal dense catalytic membrane reactor for the reaction of partial oxidation of methane to syngas (POM) was constructed from the stable mixed conducting perovskite material of BaCo_0.4Fe_0.4Zr_0.2O_3– and the catalyst of LiLaNiO/-Al₂O₃. The POM reaction was performed successfully. Not only was a short induction period of 2 h obtained, but also a high catalytic performance of 96–98% CH₄ conversion, 98–99% CO selectivity and an oxygen permeation flux of 5.4–5.8 mlcm^–2min^–1 (1.9–2.0 molm^–2S^–1Pa^–1) at 850°C were achieved. Moreover, the reaction has been steadily carried out for more than 2200 h, and no interaction between the membrane material and the catalyst took place.     

IGCC燃用低热值燃料的燃气轮机运行性能优化

天津IGCC是中国第一座整体煤气化联合循环电站。系统中燃气轮机的燃料为气化炉产生的热值较低的合成气,作为国内第一台应用于IGCC技术的燃气轮机,在运行过程中存在着合成气热值与设计值偏差大、烧嘴过热、燃烧室偏烧等问题。针对存在的问题,首先介绍了IGCC电站燃用低热值燃料的燃气轮机与普通燃气轮机在燃料、燃烧方式、燃烧器结构等方面的区别;然后结合实际运行参数分析,重点对存在的问题提出性能优化方案及措施。对燃用低热值燃料的燃气轮机后续发展具有一定的借鉴意义。     

IGCC电站控制系统工程应用及示范

以国内250 MW级IGCC电站为研究对象,根据电站的运行特性和控制要求,介绍了协调控制系统的设计、系统的基本组成、负荷指令以及气化炉和燃机的控制策略。提出了气化炉控制为主、燃机/汽机跟随的负荷控制方案,现场运行结果表明,该方案简捷有效,完全能够满足IGCC机组的控制要求。     

MnOx promotional effects on olefins synthesis directly from syngas over bimetallic Fe‐MnOx/SiO2 catalysts

The direct synthesis of lower olefins via the Fischer‐Tropsch reaction (FTO) has been performed over a series of Fe‐MnO_x/SiO₂ catalysts. The addition of MnO_x could improve the dispersion of iron species, and promote the reduction of iron oxide during the activation and subsequent carburization. Moreover, the results of characterization demonstrated that MnO_x could enhance the surface basicity of the catalysts due to electronic effects and promote the formation of iron carbides. For the first time, the intrinsic power‐law kinetics for FTO was obtained for both Fe₂₀/SiO₂ and Fe₂₀‐Mn₁/SiO₂ catalysts. Kinetic parameters and structure characterizations indicated that MnO_x could facilitate the CO dissociation on the catalyst surface, thus enhancing the adsorption strength and capacity of surface carbonaceous intermediates. The weak hydrogenation of carbonaceous species would boost the selectivities toward lower olefins. Finally, a plausible mechanism for FTO, involving the promotional effects of MnO_x on Fe, has been proposed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4451–4464, 2017     

Thermodynamic analysis and optimization of RWGS processes for solar syngas production from CO2

Process systems were investigated for syngas production from CO₂ and renewable energy (solar) by the reverse water‐gas shift (RWGS) and the reverse water‐gas shift chemical looping (RWGS‐CL) process. Thermodynamic analysis and optimization was performed to maximize the solar‐to‐syngas (StS) efficiency η_StS. Special emphasis was laid on product gas separation. For RWGS‐CL, maximum StS efficiencies of 14.2 and 14.4% were achieved without and with heat integration, respectively. The StS efficiency is dictated by the low overall efficiency of H₂ production. RWGS‐CL is most beneficial for the production of pure CO, where the StS efficiency is one percent point higher compared to that of the RWGS process with heat integration. Heat integration leads to significant reductions in external heat demand since most of the gas phase process heat can be integrated. The StS efficiencies for RWGS and RWGS‐CL achieve the same level as the reported values for solar thermochemical syngas production. © 2016 American Institute of Chemical Engineers AIChE J, 63: 15–22, 2017     

壳牌煤气化工艺流程中合成气反吹系统方案优化的探讨

介绍壳牌煤气化工艺流程中的合成气反吹系统的反吹介质可由洗涤后的粗合成气改为高温高压氮气。改造后 ,出气化装置的合成气组分既可满足下游装置的工艺要求 ,又可节省大量的工程投资     

Mg调变Ni基催化剂上甲烷部分氧化制合成气

在固定床流动反应装置上考察了不同反应条件对Ｍｇ调变Ｎｉ基催化剂反应性能的影响。当催化剂床层径高比约为２,空速２０×１０５ｈ－１,床层最高温度９４０℃,Ｖ（ＣＨ４）／Ｖ（Ｏ２）＝２０时,甲烷转化率９７％,ＣＯ选择性９８％,Ｈ２选择性接近１００％。５００ｈ的稳定性考察结果表明,甲烷转化率大于９０％,ＣＯ及Ｈ２选择性均大于９５％。反应后的催化剂经ＳＥＭ分析没观察到积炭。