【作者】 王开；

【导师】 季生福；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2009， 博士

【摘要】 随着石油储量的日趋贫乏,丰富的天然气资源的高效利用已经引起人们的关注。在天然气直接转化的研究工作中,甲烷氧化偶联（OCM）制乙烯是天然气综合利用研究的一个重要发展方向。本研究工作中主要考察了负载型催化剂和整体式催化剂上的甲烷氧化偶联催化性能,并对甲烷氧化偶联反应工艺进行了研究。主要的研究工作如下:分别以SiO₂和SBA-15分子筛为载体制备了Na-W-Mn催化剂,并考察了不同Ce、La、Bi、Sr、和Zr助剂对该催化剂的甲烷氧化偶联催化性能的影响。这些催化剂的活性结果表明,以SBA-15分子筛为载体的催化剂上甲烷氧化偶联反应催化性能高于以SiO₂为载体的催化剂上的甲烷氧化偶联反应性能;不同过渡金属的掺杂均不同程度的改变了Na-W-Mn催化剂的催化性能,其中Ce的添加可以提高Na-W-Mn催化剂的甲烷氧化偶联催化性能。分别制备了以FeCrAl合金薄片为基体的5%Na₂WO₄-2%Mn/SBA-15/Al₂O₃/FeCrAl、Li/MgO/Al₂O₃/FeCrAl金属基整体式催化剂和以堇青石（D）为基体的5%Na₂WO₄-2%Mn/SiO₂/D)陶瓷基整体式催化剂,考察了催化剂的甲烷氧化偶联反应性能。实验结果表明,对于5%Na₂WO₄-2%Mn/SBA-15/Al₂O₃/FeCrAl催化剂,1%钾改性的金属基整体式催化剂具有较好的甲烷氧化偶联催化性能。碱金属钾的添加改变了金属基整体式催化剂的酸碱性能,从而提高了催化剂的甲烷氧化偶联催化性能;对于Li/MgO/Al₂O₃/FeCrAl金属基整体式催化剂,甲烷氧化偶联催化性能随着Li含量的增加而增加,在5%Li/MgO/Al₂O₃/FeCrAl的金属基整体式催化剂上达到最大值,进一步增加Li的含量,C₂烃产物易发生深度氧化,催化剂上甲烷氧化偶联催化性能明显降低;对于不同助剂改性的5%Na₂WO₄-2%Mn/SiO₂/D陶瓷基整体式催化剂,4%的Ce改性的陶瓷基整体式催化剂具有最佳的甲烷氧化偶联反应催化性能。考察了不同Na-W-Mn/SiO₂颗粒和Na-W-Mn整体式催化剂混合床层上甲烷氧化偶联反应的催化性能,并考察了这两种催化剂床层堆积方式对甲烷氧化偶联反应性能的影响。实验结果表明,沿进料气流方向,上层为颗粒催化剂,下层为整体式催化剂的催化剂床层堆积方式可以提高甲烷氧化偶联反应中目标产物乙烯的选择性。研究了甲烷氧化偶联反应和乙烷脱氢反应的直接耦合。在实验条件下,在反应器内,沿气流方向,上层为用于OCM反应的Na-W-Mn颗粒催化剂下层为用于乙烷氧化脱氢反应的5%Cr/SBA-15/Al₂O₃/FeCrAl金属基整体式催化剂的床层堆积方式有利于耦合反应的进行,可以提高目标产物乙烯的选择性和收率。采用湿混法分别制备了碳酸盐改性的镧基、锆基和钐基氧化物催化剂并用于低温或自热甲烷氧化偶联反应。催化反应结果表明,甲烷氧化偶联反应在这些催化剂上启动后,均能够在较低的温度下或者自热进行反应。对于镧基氧化物催化剂,在V_CH4:V_O2=2.0、GHSV=18000mL·g^-1·h^-1的反应条件下,10%BaCO₃/La₂O₃催化剂能够维持230h的自热甲烷氧化偶联反应,在自热反应进行到230h时,甲烷转化率为30.12%,C₂选择性为41.9%;对于锆基氧化物催化剂,7.5%BaCO₃/ZrO₂催化剂具有最佳的低温甲烷氧化偶联催化活性;对于钐基氧化物催化剂,5.0%SrCO₃/Sm₂O₃催化剂具有最佳的自热甲烷氧化偶联催化性能,在82小时的稳定性测试中,甲烷转化率为31.4%,C₂烃的选择性为39.5%。更多还原

【Abstract】 The declining reserves of crude petroleum have led to a great interest for more efficient utilization of the aboundant natural gas resources.It has been considered that the oxidative coupling of methane（OCM） to ethane is a promising route for the direct conversion of natural gas.In this study,we studied the catalytic performance of the supported catalysts and monolithic catalysts for the OCM reaction.We also studied the effect of reaction conditions on the catalytic performance in the OCM reaction.The main research works and results are listed as follows:The Na-W-Mn catalysts were prepared using SiO₂ or SBA-15 as support, respectively.The effects of Ce,La,Bi,Sr,and Zr additives on the OCM catalytic properties were studied.The study results indicated that the OCM catalytic peroformace of the catalysts using SBA-15 as support was higher than the catalysts using SiO₂ as support.The different transition metal doping has different degrees of change in the Na-W-Mn catalysts for the OCM reaction.Adding Ce to Na-W-Mn catalysts could improve the OCM catalytic performance of the Na-W-Mn catalysts. The 5%Na₂WO₄-2%Mn/SBA-15/Al₂O₃/FeCrAl and 5%Na₂WO₄-2%Mn /SiO₂/D（dichroite） monolithic catalyst modified with different additives and Li/MgO/Al₂O₃/FeCrAl monolithic catalysts were prepared and the OCM catalytic properties of these catalysts were studied.For the 5%Na₂WO₄-2%Mn /SBA-15/Al₂O₃/FeCrAl monolithic catalysts,the 1%K modified monolithic catalyst exhibited the best the OCM catalytic performance.The addition of alkali metal potassium had changed the over style of acid-base properties of the monolithic catalyst,resulting in the improvement of the OCM catalytic performance.For the Li/MgO/Al₂O₃/FeCrAl catalysts,the OCM catalytic performance increased with higher Li content and reached the maximum at 5.0%Li/MgO/Al₂O₃/FeCrAl catalysts.Further increasing Li content,the OCM catalytic performance decreased significantly.For the 5%Na₂WO₄-2%Mn/SiO₂/D monolithic catalysts modified with different promoter,the 4%Ce modified catalyst showed the best OCM catalytic performance.The OCM catalytic performance on the mixed particle and monolithic catalyst bed was studied.The results indicated that the catalysts bed in which the upper is particle catalyst and the lower is monolithic catalyst along feed direction,could enhance the selectivity of ethene product.In addition,the direct coupling of oxidative coupling of methane and oxidative dehydrogenation（ODH） of ethane with CO₂ reaction was successful in our experiments.Under the experimental conditions,the catalysts bed in which the upper is Na-W-Mn particle catalyst for OCM reaction and the lower is 5%Cr/SBA-15/Al₂O₃ /FeCrAl monolithic catalyst for ODH reaction was benefit to enhance the selectivity and yield of ethene production in the coupling reaction.A series of carbonate/La₂O₃,carbonate/ZrO₂,and carbonate/Sm₂O₃ catalysts were prepared by wet mixing method.The catalytic activity for the low temperature or autothermal oxidative coupling of methane was evaluated in a fixed-bed micro-reactor.The results showed that these catalysts had excellent catalytic performance of low temperature or autothermal OCM reaction.For the lanthanum based catalysts,under the V_CH4:V_O2=2.0, GHSV=18000 mL·g^-1·h^-1 reaction conditions,the 10%BaCO₃/La₂O₃ catalyst could hold 230 h autothermal OCM reaction.The 30.12%CH₄ conversion and 41.9%C₂ hydrocarbon selectivity were obtained in the autothermal stability OCM reaction.For the zirconium based catalysts,the 7.5%BaCO₃/ZrO₂ catalyst showed the best low temperature OCM catalytic performance.For the samarium based catalysts,5%SrCO₃/Sm₂O₃ catalyst showed the best autothermal OCM catalytic performance.During the 82h autothermal stability test,CH₄ conversion and C₂ hydrocarbon selectivity were 31.4%and 39.5%, respectively.更多还原