This perspectives article is intended highlight the growing importance and emergence of shale gas as an energy resource and as a source of chemicals. Over the next decades huge amounts of newly discovered deposits of ...This perspectives article is intended highlight the growing importance and emergence of shale gas as an energy resource and as a source of chemicals. Over the next decades huge amounts of newly discovered deposits of trapped gas are expected to be produced not only in the USA but elsewhere providing a wealth of methane and ethane not only used for energy production, but also for conversion to lower hydrocarbon chemicals. This manuscript seeks to focus on the potential of trapped natural gas around the world. The potential new volumes of trapped gas within shale or other mineral strata coming to the marketplace offer a tremendous opportunity if scientists can invent new, cost effective ways to convert this methane to higher value chemicals. Understanding how to selectively break a single C-H bond in methane while minimizing methane conversion to C02 is critical.展开更多
利用热重分析仪,对比了不同反应温度、不同水蒸气浓度对煅烧石灰石碳酸化反应的影响。碳酸化反应温度在500℃时,反应初期水蒸气对碳酸化反应的影响并不明显,反应10 min之后,在含有1.5%、10%和20%(体积分数)水蒸气条件下碳酸化转化率比...利用热重分析仪,对比了不同反应温度、不同水蒸气浓度对煅烧石灰石碳酸化反应的影响。碳酸化反应温度在500℃时,反应初期水蒸气对碳酸化反应的影响并不明显,反应10 min之后,在含有1.5%、10%和20%(体积分数)水蒸气条件下碳酸化转化率比无水蒸气条件下转化率分别提高了19.8%、27.2%和30.5%。水蒸气的存在有助于提高碳酸化反应转化率,但随着水蒸气浓度的增加转化率增加幅度减小。利用随机孔隙模型,对产物层扩散阶段扩散系数及反应活化能进行了计算。高温条件下,气氛中含有1.5%的水蒸气使反应活化能从237.7 k J·mol-1降低到179.9 k J·mol-1,提高水蒸气浓度到10%和20%后,反应活化能从156.6 k J·mol-1降低到148.6 k J·mol-1。不同水蒸气浓度条件下,碳酸化反应存在两个明显特征:一是大约在550℃处存在一个明显扩散系数的斜率变化,这一温度与气氛中是否存在水蒸气无关;另一特征是随着反应温度的提高,水蒸气的促进作用减弱。依据实验和模型计算结果,推测了当反应处于产物层扩散阶段时水蒸气对碳酸化反应影响的作用机理。展开更多
The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various...The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector （SEM-EDX） The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.展开更多
文摘This perspectives article is intended highlight the growing importance and emergence of shale gas as an energy resource and as a source of chemicals. Over the next decades huge amounts of newly discovered deposits of trapped gas are expected to be produced not only in the USA but elsewhere providing a wealth of methane and ethane not only used for energy production, but also for conversion to lower hydrocarbon chemicals. This manuscript seeks to focus on the potential of trapped natural gas around the world. The potential new volumes of trapped gas within shale or other mineral strata coming to the marketplace offer a tremendous opportunity if scientists can invent new, cost effective ways to convert this methane to higher value chemicals. Understanding how to selectively break a single C-H bond in methane while minimizing methane conversion to C02 is critical.
文摘利用热重分析仪,对比了不同反应温度、不同水蒸气浓度对煅烧石灰石碳酸化反应的影响。碳酸化反应温度在500℃时,反应初期水蒸气对碳酸化反应的影响并不明显,反应10 min之后,在含有1.5%、10%和20%(体积分数)水蒸气条件下碳酸化转化率比无水蒸气条件下转化率分别提高了19.8%、27.2%和30.5%。水蒸气的存在有助于提高碳酸化反应转化率,但随着水蒸气浓度的增加转化率增加幅度减小。利用随机孔隙模型,对产物层扩散阶段扩散系数及反应活化能进行了计算。高温条件下,气氛中含有1.5%的水蒸气使反应活化能从237.7 k J·mol-1降低到179.9 k J·mol-1,提高水蒸气浓度到10%和20%后,反应活化能从156.6 k J·mol-1降低到148.6 k J·mol-1。不同水蒸气浓度条件下,碳酸化反应存在两个明显特征:一是大约在550℃处存在一个明显扩散系数的斜率变化,这一温度与气氛中是否存在水蒸气无关;另一特征是随着反应温度的提高,水蒸气的促进作用减弱。依据实验和模型计算结果,推测了当反应处于产物层扩散阶段时水蒸气对碳酸化反应影响的作用机理。
文摘The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector （SEM-EDX） The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.
