甲烷-二氧化碳重整制合成气与现代分析技术应用于探究性化工专业实验的设计与探索

以甲烷-二氧化碳重整制合成气为实例,设计探究性实验,将合成气的制备和现代分析技术应用于化工专业实验的教学实践中以提高学生的创新和实践能力。实验包括催化剂的制备,催化剂的性能评价和催化剂的表征等3大部分。采用工业最常用的浸渍法制备含有不同助剂的Ni/X/γ-Al2O3(X为Co,Fe,MgO,CeO2)催化剂,以甲烷-二氧化碳重整反应评价其催化性能,并采用XRD、H2-TPR、BET和TG对催化剂的微观结构进行表征。结合催化剂的性能评价结果和表征结果,探讨不同助剂对镍基催化剂性能的改善效果及机制。通过开设该实验,可以让学生了解化工学科的前沿知识以及现代分析技术的基本原理和用途,掌握专业的实验操作、数据处理和谱图绘制方法,提高学生的专业素养和综合能力。

甲烷与二氧化碳重整制取合成气研究进展

甲烷 二氧化碳重整制取高附加值合成气的过程是近十几年来世界范围的研究热点之一,该过程的研究具有重要的理论和实际意义。本文综述了甲烷 二氧化碳重整制取合成气反应的进展,对重整催化剂、积炭过程、非常规供能方式在重整反应中的应用等进行了讨论和分析。

沉淀剂对CH_4-CO_2重整Ni/MgO催化剂结构和性能的影响

分别采用氢氧化钾和碳酸钾溶液为沉淀剂,制备了两种Ni/MgO催化剂(依次标记为NM1、NM2),用BET、XRD、TPR、TG及活性评价等方法考察了沉淀剂对Ni/MgO催化剂的物化性质和催化性能的影响。研究结果表明,两种催化剂中的镍物种虽均以镍镁固溶体形式存在,但还原性能存在明显差异,NM1中镍物种与载体具有较强的相互作用。与NM2相比,NM1具有较大的比表面和较小的镍镁固溶体晶粒度,还原后的NM1催化剂中镍晶粒也相对较小。在CH4 CO2重整反应中,NM1呈现了较高的催化活性和选择性。

CH_4-CO_2重整炭基催化剂的制备及应用研究

以神华集团煤直接液化残渣为原料,采用KOH活化法,经炭化、活化一体反应制得炭基催化剂。利用TG、SEM、BET、XRD等表征分析,确定了炭基催化剂的制备条件,探究了炭基催化剂的失重行为、碱炭比、比表面积及孔径的大小等因素对CH_4-CO_2重整制合成气反应催化活性的影响。结果表明在经过KNO_3预氧化、碱炭质量比为3的KOH活化条件下制备的炭基催化剂,收率为43.3%、比表面积达到1632m^2/g,该催化剂在CH_4-CO_2重整反应中具有良好的催化效果,可使CH_4和CO_2的转化率均达90%以上。

Insight into MgO promoter with low concentration for the carbon-deposition resistance of Ni-based catalysts in the CO_2 reforming of CH_4

The CO2reforming of CH4is studied over MgO‐promoted Ni catalysts,which were supported on alumina prepared from hydrotalcite.This presents an improved stability compared with non‐promoted catalysts.The introduction of the MgO promoter was achieved through the‘‘memory effect’’of the Ni‐Al hydrotalcite structure,and ICP‐MS confirmed that only0.42wt.%of Mg2+ions were added into the Ni‐Mg/Al catalyst.Although no differences in the Ni particle size and basicity strength were observed,the Ni‐Mg/Al catalyst showed a higher catalytic stability than the Ni/Al catalyst.A series of surface reaction experiments were used and showed that the addition of a MgO promoter with low concentration can promote CO2dissociation to form active surface oxygen arising from the formation of the Ni‐MgO interface sites.Therefore,the carbon‐resistance promotion by nature was suggested to contribute to an oxidative environment around Ni particles,which would increase the conversion of carbon residues from CH4cracking to yield CO on the Ni metal surface.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Reforming of Methane by CO2 over Bimetallic Ni-Mn/γ-Al2O3 Catalyst

γ-Al2O3 supported Ni-Mn bimetallic catalysts for CO2 reforming of methane were prepared by impregnation method. The reforming reactions were conducted at 500-700℃ and atmospheric pressure using CO2/CH4/N2 with feed ratio of 17/17/2, at total flow rate of 36 mL/min. The catalytic performance was assessed through CH4 and CO2 conversions, synthesis gas ratio （H2/CO） and long term stability. Catalytic activity and stability tests revealed that addition of Mn improved catalytic performance and led to higher stability of bimetallic catalysts which presented better coke suppression than monometallic catalyst. In this work, the optimum loading of Mn which exhibited the most stable performance and least coke deposition was 0.5wt%. The fresh and spent catalysts were characterized by various techniques such as Brunauer-Emmett-Teller, the temperature programmed desorption CO2- TPD, thermogravimetric analysis, X-ray diffraction, scanning electron microscope, EDX, and infrared spectroscopy.

国内外熔融高炉渣显热回收方法

分析了熔融高炉渣显热回收的必要性。因为熔渣的物理性质和高炉出渣不连续性,导致熔渣显热回收存在困难。介绍了滚筒法、搅拌法、风淬法、连铸法、离心粒化和反应热法显热回收工艺,并指出甲烷-二氧化碳重整法有很好的发展前途。

镍基稀土改性催化剂的研究

通过对镍基稀土改性催化剂TPR的研究 ,结果表明稀土氧化物La2 O3 添加到Ni/α -Al2 O3 中改变了镍铝的相互作用 ,添加CeO2 、MgO助剂能够有效地提高活性组份镍的分散度。

Kinetic Study on CO_2 Reforming of Methane

The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio ＞ 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.

Novel synthesis of nickel oxide microsphere with high surface area and its catalytic application for carbon dioxide reforming of methane

Nickel oxide(NiO)microsphere with a large surface area was novelly synthesized through nickel bicarbonate(Ni(HCO3)2)precursor.The obtained nickel oxide(NiO)microsphere was characterized by X-ray pattern diffraction,scanning electron microscopy,CO2 temperature-programmed desorption,H2 temperature-programmed reduction,N2 adsorption/desorption and laser scattering particle size distribution analyzer.It was found that nickel oxide(NiO)synthesized by the thermal decomposition of Ni(HCO3)2through area hydrolysis,presented very nice microsphere with high surface area.The catalytic properties of obtained nickel oxide(NiO)microsphere were studied in the reaction of carbon dioxide reforming of methane where 91.3% conversion of CH4 with 93% conversion of CO2 was observed.Besides,the catalyst maintained high stability over 200 h on the stream.

Hydrogen production through CO_2 sorption-enhanced methane steam reforming:Comparison between different adsorbents

A two-dimensional transient model has been developed to describe the catalytic methane reforming （MSR） coupled with simultaneous CO2 removal by different absorbents under non-isothermal, non-isobaric and non-adiabatic operating conditions. The influences of temperature, pressure and steam/carbon （S/C） on enhancement were taken into account. The results showed that the hydrogen mole fraction （dry basis） higher than 94% could be achieved using Li4SiO4, CaO, and HTC as CO2 acceptors at the operating conditions of 550~C and 0.1 MPa. When the reaction temperature varied from 500℃ to 600℃, the initial CO2 capture rates were HTC〉CaO〉Li4SiO4〉LizZrO3, and the saturation rates HTC〉CaO〉Li4SiOg〉Li2ZrO3. Increasing the reaction temperature would improve the CO2 capture rate and available CO2 capacity. For Li4SiO4, although the adsorbing rate increased as the operating temperature increased, the capacity almost did not change. At 550℃, increasing the working pressure could promote the enhancing factors of Li4SiO4,Li2ZrO3 and HTC. There was an optimal steam/carbon ratio between 2-4.5 such that all CaO, Li4SiO4, HTC and Li2ZrO3 would obtain the biggest enhancement for H2 production at the pre-breakthrough stage.

Promotional effect of cerium on nickel-containing mesoporous silica for carbon dioxide reforming of methane

A series of Ce-promoted 6.7%Ni-containing mesoporous silica(Ce-Ni-Si O2)with varying Ce content(0.5%–4.8%)was prepared using the evaporation-induced self-assembly method.The characterization results showed that Ce and Ni species were homogeneously incorporated into the mesoporous silica matrix.The catalytic properties of these samples in the dry reforming of methane reaction revealed that the catalysts(e.g.,1.2%Ce-Ni-Si O2)containing highly dispersed small Ni particles exhibited excellent catalytic activity and long-term stability,which is attributed to the anchoring effect of the Ce and its ability to increase surface oxygen species concentration.