国外碳－化学技术进展

综述了近年来国外Ｃ１化学，包括甲烷化学、甲醇化学、合成气化学和ＣＯ２化学等技术进展。     

合成气在K－Fe－MnO／Silicalite－2催化剂上转化为低碳烯烃的研究 I．K_2O助剂的作用

Ｋ２Ｏ是催化剂Ｆｅ－ＭｎＯ／Ｓｉｌｉｃａｌｉｔｅ－２由合成气制低碳烯烃的有效助剂，Ｋ２Ｏ能明显提高催化剂活性及低碳烯烃选择性。Ｋ２Ｏ助剂将抑制部分铁的还原，但能增强催化剂对ＣＯ的吸附能力，从而能提高催化剂活性，抑制甲烷的生成，Ｋ２Ｏ助剂能抑制乙烯在催化剂表面的二次反应（尤其是乙烯的歧化反应），从而提高ＣＯ／Ｈ及反应制低碳烯烃的选择性。     

CO+H2经F-T反应途径选择性合成汽油馏分异构烷烃

采用两段串联固定床反应器,以Co/SiO₂ 作为F-T合成催化剂,以β分子筛负载金属作为加氢裂解/异构化催化剂,研究了从合成气经F-T反应途径一步法选择性合成汽油馏分异构烷烃的反应性能。结果表明,两段固定床系统的F-T合成产物主要为C₁～C₁₀烃,而且异构烷烃的选择性较高（I/C⁺₄≈70%）。同时,钯盐前驱体对0.5%Pd/β的加氢裂解/异构化反应性能有很大影响。保持金属总负载质量分数为0.5%,在Pd/β中引入少量Pt或Ni,可以明显改善催化剂活性和稳定性。     

合成气一步法制二甲醚催化剂研究进展

简述了二甲醚的物化特性及其应用前景,对现有的几种合成气一步法合成二甲醚的反应机理及动力学模型进行了概述。分别研究了双功能催化剂中的甲醇合成活性组分和甲醇脱水活性组分,CuO/ZnO/Al₂O₃ 作为甲醇合成组分,活性和稳定性较好,甲醇脱水活性组分以γ-Al₂O₃ 、分子筛及其改性后产物较为常用。探讨了双功能催化剂的制备方法及改性方法。     

反应压力对HZSM-5分子筛催化剂上合成气经二甲醚制取芳烃反应的影响

在2个等压串联连续流动同定床反应器内考察了合成气经由二甲醚制取芳烃的反应性能.一段合成二甲醚反应采用Cu/Zn/Al_2O_3和γ-Al_2O_3复合催化剂;二段合成芳烃反应采用HZSM-5(Si/Al=38)催化剂.考察了反应压力对合成芳烃反应的影响,并分析了产物的分布规律.结果表明:在T_1=270℃,T_2=360℃,GHSV=500 h~(-1)条件下,反应压力由2 NPa增加到4 MPa时,芳烃选择性轻微降低,由86.75%降低到83.67%,同时CO转化率从72.47%升高到84.34%,产物中均四甲苯的选择性增加不明显.而当压力增加到5 NPa时,芳烃选择性降低到63.51%,而异构烷烃选择性提高5倍多.反应压力增加,反应平衡倾向于加氢异构化反应;反应压力在2～4 NPa时,有利于芳烃的合成.     

Methane steam reforming at microscales: Operation strategies for variable power output at millisecond contact times

The potential of methane steam reforming at microscale is theoretically explored. To this end, a multifunctional catalytic plate microreactor, comprising of a propane combustion channel and a methane steam reforming channel, separated by a solid wall, is simulated with a pseudo 2‐D (two‐dimensional) reactor model. Newly developed lumped kinetic rate expressions for both processes, obtained from a posteriori reduction of detailed microkinetic models, are used. It is shown that the steam reforming at millisecond contact times is feasible at microscale, and in agreement with a recent experimental report. Furthermore, the attainable operating regions delimited from the materials stability limit, the breakthrough limit, and the maximum power output limit are mapped out. A simple operation strategy is presented for obtaining variable power output along the breakthrough line (a nearly iso‐flow rate ratio line), while ensuring good overlap of reaction zones, and provide guidelines for reactor sizing. Finally, it is shown that the choice of the wall material depends on the targeted operating regime. Low‐conductivity materials increase the methane conversion and power output at the expense of higher wall temperatures and steeper temperature gradients along the wall. For operation close to the breakthrough limit, intermediate conductivity materials, such as stainless steel, offer a good compromise between methane conversion and wall temperature. Even without recuperative heat exchange, the thermal efficiency of the multifunctional device and the reformer approaches ～65% and ～85%, respectively. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Numerical comparison of premixed laminar flame velocity of methane and wood syngas

The laminar flame velocity of a synthetic gas is calculated numerically with PREMIX and is compared to methane laminar flame velocity. The calculations are performed at different equivalence ratios, initial mixture temperatures and pressures. For each fuel, a correlation for the laminar flame velocity is presented in the form . The low heating value syngas yields a slower laminar flame velocity than methane, especially around stoichiometry. The laminar flame velocities of methane and wood residue syngas react similarly to the effect of pressure, while numerical results suggest that the laminar flame velocity of syngas is more sensitive to the increase of mixture initial temperature.     

Biomass-derived CO2 rich syngas conversion to higher hydrocarbon via Fischer-Tropsch process over Fe–Co bimetallic catalyst

Biomass-derived syngas (CO₂ + CO + H₂) has emerged as a potential non-fossil fuel source to yield transportation fuel via Fischer Tropsch Synthesis (FTS) reaction. Thus, the present study demonstrates the conversion of CO₂ containing syngas into fuel range hydrocarbon via Fischer Tropsch Synthesis over Fe–Co bimetallic catalyst. The experimental tests were carried out in a fixed bed continuous reactor to investigate the effect of CO₂ on CO/CO₂ conversion. Accordingly, obtained data were validated by FTS kinetic model for a plug flow reactor. It was found that the unique combination of Fe and Co bimetallic catalyst facilitates both FTS and water gas shift (WGS) reaction simultaneously that helps to convert CO₂ along with CO. It was also observed that the presence of iron in the catalyst helps in conversion of CO₂ into hydrocarbons, only when a particular concentration of CO₂ in syngas is reached, i.e., critical ratio R_C (CO₂/CO + CO₂) due to the occurrence of reverse water gas reaction (RWGS) which varies with the temperature and the feed gas composition (H₂/CO/CO₂ molar ratio). At 240 °C and hydrogen deficient condition, the critical ratio was measured to be 0.74 whereas for hydrogen balanced condition, it was measured 0.6. The kinetic model developed in the present study predicted trends for % CO conversion, % carbon conversion, and % CO₂ conversion which is applicable for a wide range of critical ratio R_C (CO₂/(CO + CO₂) = 0 to 1). The model also predicted that a positive conversion of CO₂ could be achieved at lower CO₂ concentration by increasing the reaction temperature. At 260 °C and 280 °C, the value of Rc were 0.31 and 0.18 were measured.     

Energy and economic aspects of synthesis gas production from oil sludge and plastic waste

A series of experiments have been performed to investigate the influence of reaction temperature, the equivalence ratio (ER), and blending ratio on the gas composition, tar content and higher heating value (HHV) of synthesis gas. H₂ content decreased from 10.7 to 8.2% in the range of BR while CO and CH₄ increased from 17.4 to 23.1% and 3.4 to 6.3%, respectively. HHV increased with BR and H₂/CO showed an opposite trend. The highest HHV and H₂/CO were obtained at 100%PW and 100%OS, respectively. Tar content increased from 4.8 to 9.5?g/Nm³ with BR increasing in the range because of a reduction in the endothermic nature of volatile combustion.     

ANN modeling of fuel gas production from low-grade residual oil

The aim of this work is to develop an artificial neural network model to simulate fuel gas production from low-grade residual oil. Effect of operating conditions on the fuel gas composition and performance parameters was studied. The model was validated against the experimental data and found to be in a good agreement. Since oxygen ratio increase improves the nature of water-gas reaction, increased oxygen content moved the reaction toward products and as a result CO and H₂ increased. Increased ER highly increased the CO₂ and highly decreased CH₄, CO and H₂ because increased ER means the movement of the process towards combustion.