共查询到16条相似文献,搜索用时 125 毫秒
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目前,不少焦化厂的煤气净化工艺中,用催化分解炉在1000~1200℃下将氨分解成氮气和水,催化剂是由氧化镁作载体的负载活性镍构成的固体催化剂,氨分解炉内一般需充填8~10t催化剂,而价值高达上百万元。为此,如何延长催化剂的使用寿命,就成为降低生产成本重要环节。1影响催化剂寿命的因素氨气进入氨分解炉后,在空速一定时,氨的分解率与催化剂所含的活性镍有关,一般国产催化剂使用一年左右后,就会因活性镍减少,难以达到要求的氨分解率而更换新催化剂。催化剂失活的原因有以下两个方面:(1)镍损耗。主要是升华损耗,由… 相似文献
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马格尼托哥尔斯克钢铁股份有限公司焦化厂焦炉煤气回收车间极其重视氨分解炉用催化剂活性的控制问题,并研究了在煤气净化过程中催化剂活性对整个脱氨工艺效果的影响。 相似文献
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我厂的氨分解装置采用的是热催化技术,即在还原氛围下,氨和氰化氢经高温催化分解成氮、氢和一氧化碳。因氨分解炉是核心设备,仅炉内所装填催化剂的价值就高达100万元,在保证氨分解效率的前提下,如何延长催化剂的使用寿命,则是我们日常工作的重点。1氨分解催化剂的损耗原因我们所用的氨分解催化剂是以氧化镁为载体,镍是主要活性成分。生产实践表明,在氨分解过程中造成催化剂损耗的原因有如下几方面。(1)虽然氨的分解需在高温下进行,但当温度超过1200℃时,会使镍蒸汽压过高而加快镍的流失。当炉温低于900℃时,则易发… 相似文献
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镍基钙钛矿分解氨制取氢气虽有稳定性好、价格低廉的优点,但也有完全分解温度偏高的缺点。为降低完全分解氨制取氢气的温度,实验采用柠檬酸络合法,通过改变A位掺杂离子与掺杂量对LaNiO3改性,并改变载体及负载量,制备一系列的催化剂。采用XRD、SEM、TEM表征技术进行表征,考察了Ba 含量对催化剂结构与性能的影响。实验表明在催化剂装填量为1mL、空速为10000h-1、原料气为纯氨的条件下,氨分解的最佳电子助剂离子为Ba、最优催化剂为w(NiO)=20%的La0.9Ba0.1NiO3/MCM-41,氨气完全分解温度由650℃降为575℃。随着Ba掺杂量的增加,催化剂活性先增加,在x=0.1达到最大值,之后减小,掺杂Ba过多催化剂的结构由钙钛矿变为非钙钛矿,非钙钛矿结构的催化剂活性不如钙钛矿。 相似文献
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采用溶胶凝胶法,制备了负载型镍基钙钛矿型催化剂,并在常压微反应装置上对其氨分解催化活性进行了评价。采用BET、XRD、TPR、TEM等方法对催化剂进行表征。研究结果表明,以MCM-41分子筛为载体的催化剂,由于其较大的比表面积和规整的介孔结构,使活性组分能够很好地分散在载体表面,有利于增加有效活性位,提高活性组分的反应能力,表现出很好的氨分解催化活性。以NiO计,负载量为20%的LaNiO3/MCM-41具有比非负载的LaNiO3更好的催化活性,这样不仅提高了催化活性,还大大地减少了活性组分用量,降低了生产成本,从而具有很好的应用前景。 相似文献
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Bimetallic Ru-Fe Nanoparticles Supported on Carbon Nanotubes for Ammonia Decomposition and Synthesis
Cai Chen Yiwen Chen Arshid M. Ali Wenjia Luo Jie Wen Lianhong Zhang Hui Zhang 《化学工程与技术》2020,43(4):719-730
Alloy catalysts can achieve superior performance to single metal while reducing the cost by fine-tuning the composition and morphology. Bimetallic Ru-Fe nanoparticles were synthesized via liquid-phase reduction method followed by impregnation with multiwall carbon nanotubes (CNTs) to prepare Ru-Fe/CNTs catalysts. The Ru3Fe/CNTs catalyst yields a superior catalytic stability for ammonia decomposition compared to the Ru/CNTs catalyst. Hence, the ammonia synthesis rate of the Ru3Fe/CNTs catalyst was significantly higher than that of Ru/CNTs catalyst. The potential of bimetallic catalysts with reasonable composition and proportion will expand the research of efficient catalysts for ammonia decomposition and synthesis. 相似文献
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Activity of cobalt and iron catalysts in ammonia synthesis was determined under a pressure of 10 MPa and at the temperature range of 673–823 K, in a six-channel integral steel reactor. The catalytic ammonia decomposition was studied in a differential reactor under the atmosphere of low concentration of ammonia (<6%) in the temperature range of 673–823 K under atmospheric pressure. The determined values of the activation energy for the ammonia synthesis reaction over cobalt and iron catalysts are 268 and 180 kJ/mol, respectively, whilst for the ammonia decomposition reaction they are equal to 111 and 138 kJ/mol. The cobalt catalyst showed lower activity than a commercial iron catalyst in ammonia synthesis reaction. The cobalt catalyst turned out to be more effective in ammonia decomposition reaction than the iron one. 相似文献
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Catalytic ammonia decomposition: COx-free hydrogen production for fuel cell applications 总被引:2,自引:0,他引:2
Catalytic decomposition of ammonia has been investigated as a method to produce hydrogen for fuel cell applications. The absence of any undesirable by-products (unlike, e.g., COx, formed during reforming of hydrocarbons and alcohols) makes this process an ideal source of hydrogen for fuel cells. In this study a variety of supported metal catalysts have been studied. Supported Ru catalysts were found to be the most active, whereas supported Ni catalysts were the least active. The supports were found to play a profound role in the ammonia decomposition process. The activation energies for the ammonia decomposition process varied from 17 to 22 kcal/mol depending upon the catalyst employed. The activation energies of the supported Ir catalysts were found to be in excellent agreement with our recent studies addressing ammonia decomposition on single crystal Ir. 相似文献
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用浸渍法制备Ni/Al_2O_3和Ni/xMo-Al_2O_3催化剂,以氨分解为模型反应,考察Ni负载量、焙烧温度、溶剂和助剂等合成条件对催化剂催化性能的影响,通过XRD和TG-DTG表征方法对催化剂进行表征。结果表明,最佳合成条件:Ni负载质量分数为16%,焙烧温度350℃,采用丙酮为溶剂制备的Ni/Al_2O_3催化剂具有较好的催化活性。500℃添加质量分数3%的助剂Mo可以使Ni/Al_2O_3催化剂的活性显著提高39%,Ni/3%Mo-Al_2O_3催化剂的氨分解率达93.5%。 相似文献
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The dissolution process of metal oxide catalysts in the alcoholysis of urea by 1, 2-propylene glycol (PG) to the synthesis of propylene carbonate (PC) was investigated. It was found that the reaction was mainly catalyzed by homogeneous catalysts. The metal oxide reacted with ammonia and isocyanate acid, the decomposition products of urea, to form a complex and dissolved into the reaction system. The dissolved amount of catalyst was positively correlated with the PC yield by using different oxides and salts as catalysts. The Fourier-transform infrared spectroscopy (FTIR) result of the catalysts reacting with urea showed that the dissolution-precipitation process of the catalysts was related to the decomposition of urea. The results of catalytic test indicated that both the dissolved amount of catalysts and the structure of the complex affected PC yields. A reaction mechanism was proposed based on the results. From the mechanism, a complex catalyst with at least two ammonia ligands is better for this reaction. 相似文献