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1.
Recent progress in methane dehydroaromatization: From laboratory curiosities to promising technology
Shuqi Ma Xiaoguang Guo Lingxiao Zhao Susannah Scott Xinhe Bao 《Journal of Energy Chemistry》2013,22(1):1-20
Direct conversion of methane to benzene or other valuable chemicals is a very promising process for the efficient application of natural gas. Compared with conversion processes that require oxidants, non-oxidative direct conversion is more attractive due to high selectivity to the target product. In this paper, an alternative route for methane dehydrogenation and selective conversion to benzene and hydrogen without the participation of oxygen is discussed. A brief review of the catalysts used in methane dehydroaromatization (MDA) is first given, followed by our current understanding of the location and the active phase of Mo species, the reaction mechanism, the mechanism of carbonaceous deposit and the deactivation of Mo/zeolite catalysts are systematically discussed. Ways to improve the catalytic activity and stability are described in detail based on catalyst and reaction as well as reactor design. Future prospects for methane dehydroaromatization process are also presented. 相似文献
2.
Tianyu Zhang 《Chemical science》2021,12(38):12529
The direct conversion of methane to high-value chemicals is an attractive process that efficiently uses abundant natural/shale gas to provide an energy supply. The direct conversion of methane to high-value chemicals is an attractive process that efficiently uses abundant natural/shale gas to provide an energy supply. Among all the routes used for methane transformation, nonoxidative conversion of methane is noteworthy owing to its highly economic selectivity to bulk chemicals such as aromatics and olefins. Innovations in catalysts for selective C–H activation and controllable C–C coupling thus play a key role in this process and have been intensively investigated in recent years. In this review, we briefly summarize the recent advances in conventional metal/zeolite catalysts in the nonoxidative coupling of methane to aromatics, as well as the newly emerging single-atom based catalysts for the conversion of methane to olefins. The emphasis is primarily the experimental findings and the theoretical understanding of the active sites and reaction mechanisms. We also present our perspectives on the design of catalysts for C–H activation and C–C coupling of methane, to shed some light on improving the potential industrial applications of the nonoxidative conversion of methane into chemicals.The direct conversion of methane to high-value chemicals is an attractive process that efficiently uses abundant natural/shale gas to provide an energy supply. 相似文献
3.
担载型钴镍金属氧化物催化剂上CH4还原NO反应研究 总被引:3,自引:0,他引:3
NOx是大气的主要污染物之一,近年来,利用甲烷选择还原NOx引起了广泛关注,研究发现,Co、Mn和Ni离子交换的ZSM-5分子筛具有较高的活性[1~3].但金属离子交换的分子筛催化剂有热稳定性差、易失活等缺点.最近已有金属氧化物用作甲烷还原NOx反应... 相似文献
4.
考察了具有相同金属分散度的Pt/NaY、Pt/HNaY、 Pt/HY、Pt/NaBeta和Pt/HBeta催化剂中沸石载体的酸性对在低温下(≤250 ℃)甲烷两步等温转化反应以及由甲烷解离吸附产生的表面碳物种分布的影响。由甲烷等温两步转化生成的C2+烃类产物的总量随着载体酸性的增加而明显增加;C2~C6产物的分布也发生了变化。由表面碳物种的程序升温加氢结果表明,在各种催化剂上碳物种的形式是相似的,其总量和具有活性的Cα物种的量均因载体酸性增加而增加,反应性也增大。这种因沸石载体酸性变化而引起的载体效应是由金属和载体的相互作用造成负载在酸性载体上铂粒子的贫电子性而引起,即由金属粒子电子性质的变化而引起的催化性质的变化。 相似文献
5.
The principal methods for the conversion of methane into useful chemical compounds are discussed. Promising methods include direct nonoxidative dehydrocondensation of methane to aromatic hydrocarbons, oxidative coupling of methane to ethylene, and partial oxidation of methane to oxygenates. In the case of the last reaction the proposed approach makes it possible to compare precisely the selective action of heterogeneous catalysts and to predict that a maximum yield will be obtained in a flow-type reactor with recycling. 相似文献
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7.
V. R. Choudhary V. H. Rane S. T. Chaudhari 《Reaction Kinetics and Catalysis Letters》1998,63(2):371-377
Pulse reaction of methane in the presence and absence of free (or gaseous) oxygen and that of ethane and ethylene in the absence
of free oxygen over Li−MgO, La−MgO and Sm−MgO (Li or La or Sm/Mg ratio=0.1) have been investigated for elucidating the role
of lattice and free oxygen in oxidative coupling of methane (OCM) over these catalysts. No significant role is played by the
lattice oxygen from these catalysts in the OCM process. The presence of free oxygen is essential for all these catalysts to
be active and selective in OCM process. However, lattice oxygen plays some role in ethane conversion but a very significant
role in ethylene conversion over these catalysts. 相似文献
8.
S. I. Galanov A. G. Zherlitsyn Yu. V. Medvedev O. I. Sidorova V. P. Shiyan 《Russian Journal of Applied Chemistry》2011,84(6):997-1002
Effect of a microwave field on metallic catalysts was studied in the reaction of decomposition of methane into hydrogen and
highly dispersed carbon. The dependence of the conversion of methane, yield of carbon, and its composition on the chemical
nature of a catalysts and reaction conditions was examined. 相似文献
9.
TinghuaWu Mingqiao Zhu Zhenjiang Niu Yijun Zhong Yan Guan Ya Liu Qiangu Yan Zelin Li Huilin Wan 《天然气化学杂志》2002,11(3):159-164
The catalytic properties of several supported metal catalysts on different carriers were studied in the partial oxidation of methane (POM) to syngas. In our experiment, supported noble metal catalysts exhibited better performance than the other supported transition metal catalysts. The catalyst performances were significantly influenced by the d-electron configuration of the active metal components and the dispersion of active metal components on the support. A catalyst with a moderate number of unpaired electrons in the d-orbital of the active metal support without obvious acidity or redox activity (e.g. MgO) was suitable for POM performance. The Rh/SiO2 catalyst was the best in the POM reaction, among those investigated. Reaction conditions apparently also affected the POM performance of the catalyst. The conversion of methane and the selectivity for CO increased with the reaction temperature, and a high CH4/O2 ratio was not beneficial for POM performance. 相似文献
10.
Tinghua Wu Mingqiao Zhu Zhenjiang Niu Yijun Zhong Yan Guan Ya Liu Qiangu Yan Zelin Li Huilin WanZhejiang Normal University Institute of Physical Chemistry Jinhua ChinaZhejiang University Department of Chemical Engineering Hangzhou ChinaXiamen University Department of Chemistry Xiamen China 《天然气化学杂志》2002,(Z2)
The catalytic properties of several supported metal catalysts on different carriers were studied in the partial oxidation of methane (POM) to syngas. In our experiment, supported noble metal catalysts exhibited better performance than the other supported transition metal catalysts. The catalyst performances were significantly influenced by the d-electron configuration of the active metal components and the dispersion of active metal components on the support. A catalyst with a moderate number of unpaired electrons in the d-orbital of the active metal support without obvious acidity or redox activity (e.g. MgO) was suitable for POM performance. The Rh/SiO2 catalyst was the best in the POM reaction, among those investigated. Reaction conditions apparently also affected the POM performance of the catalyst. The conversion of methane and the selectivity for CO increased with the reaction temperature, and a high CH4/O2 ratio was not beneficial for POM performance. 相似文献
11.
The high-temperature complete oxidation of methane over metallic monolith-supported zeolite catalysts containing isolated Mn, Co, and Pd ions was studied. The reaction involves heterogeneous and heterogeneous-homogeneous catalytic processes. The ratio between these processes depends on the temperature, feed rate, and the amount of catalyst charged in the reactor. In the heterogeneous catalytic process, the activity of the catalysts supported on the Fe—Cr—Al monolithic alloy decreases in the series Pd > Mn > Co > Fe—Cr—Al monolith and the reaction rate uniformly increases with increasing contact time. In the heterogeneous-homogeneous process, the reaction rate drastically increases and a 100% conversion of methane to CO2 can be achieved by minor variations of the contact time. In this case, methane oxidation depends not only on the catalyst chemical composition but also on its external surface area and the reaction volume. 相似文献
12.
Various VOx/SiO2 catalysts were prepared by the methods of physical mixing, conventional wetness impregnation and ultrasonication-assistant impregnation. The catalysts were characterized by XRD, UV-Vis DRS, Raman, TPR, ESR and TPSR techniques and the nature of the vanadium species were correlated to their catalytic performance in the reaction of direct conversion of methane to formaldehyde. It is concluded that highly dispersed monomeric and low oligomeric vanadia species are formed on the sample prepared with both traditional wetness impregnation method and ultrasonication-assistant impregnation, whereas in the latter case, the amount of oligomeric vanadia species is much smaller. The V2O5 microcrystallines are the dominant species on the material prepared by physical mixing method. During the selective oxidation of methane, Vv species are reduced to V^IV paramagnetic species and both microcrystalline V205 species and oligomeric vanadia species are found to further disperse and transform into tetrahedral vanadia species. Based on the results of UV Raman spectroscopy and TPSR, C02 is suggested to be formed via two different routes, in which one is from the sequence reaction of CH4→ HCHO→ CO → CO2 over monomeric vanadia species, and the other is from the direct oxidation of methane to CO2 over oligomeric vanadia species. Oligomeric vanadia species is more active than monomeric vanadia species for methane activation. 相似文献
13.
J. K. S. Wan Y. G. Chen Y. J. Lee M. C. Depew 《Research on Chemical Intermediates》2000,26(6):599-619
Conversion of methane to higher hydrocarbon products, in particular, aromatic hydrocarbons has been achieved with good methane
conversion and selectivity to aromatic products over heterogeneous catalysts using both high power pulsed microwave and rf
energy. For example, under microwave irradiation > 85% conversion of methane and 60% selectivity to aromatics could be achieved.
Cu, Ni, Fe and Al metallic materials are highly effective catalysts for the aromatization of methane via microwave heating;
however, with a variety of supported catalysts the major products were C2 hydrocarbons and the conversion of methane was low. The use of sponge, wire and net forms of these metal catalysts was found
advantageous in effective methane conversion. The reactions are considered to be free radical in nature and to proceed through
an intermediate stage involving formation of acetylene. The influence of catalyst nature and configuration, as well as the
microwave and rf irradiation parameters on the reaction efficiency and product selectivity has been examined in both batch
and continuous flow conditions. 相似文献
14.
在流化床反应器中, 考察了 Ni/SiO2 催化剂上 CH4 或 CH4-C3H8 临氧 CO2 重整 (自热重整) 制合成气反应性能. 结果表明, 在 CH4-C3H8 混合气自热重整反应中, Ni 粒径较小催化剂的活性和抗积炭性能较高, CH4 和 CO2 转化率分别达 75.5% 和 72.6%. C3H8 比 CH4 更易解离及被氧化, 部分 C3H8 解离出来的中间产物 CHx 物种可与吸附 H 结合为 CH4, 因而降低了 CH4 的表观转化率; CHx 也可与吸附的 CO2 物种反应生成 H2 与 CO, 从而促进了 CO2 的转化. 相似文献
15.
Effect of CeO2 preparation method and Cu loading on CuO/CeO2 catalysts for methane combustion
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CeO2 was synthesized by sol-gel, hydrothermal, nitrate thermal decomposition methods, respectively, and used as support to prepare CuO/CeO2
catalysts. According to characterization and reaction results, preparation method of CeO2 had a great influence on the physicochemical
properties and activities of CuO/CeO2 catalysts. CuO with high dispersion and strong interaction with CeO2 was highly active in methane
combustion, while CuO particles less associated with CeO2 showed less activity. The CuO catalyst supported on CeO2 which was prepared via
nitrate thermal decomposition method showed the largest area, the smallest particle size, the highest dispersion of copper species and strong
support metal interactions. Therefore, it presented the highest redox ability and activity for methane combustion. Activities of the catalysts
with different copper content kept increasing until 5% Cu loading and from then on kept constant. Moreover, methane conversion decreased
as methane space velocities increased on CuO/CeO2 catalyst. Addition of CO2 to the feed did not produce a significant effect on the catalytic
activity, but the presence of H2O provoked a remarkable decrease on the activity of CuO/CeO2 catalyst. 相似文献
16.
Dossumov K. Ergazieva G. E. Ermagambet B. T. Myltykbaeva L. K. Telbaeva M. M. Mironenko A. V. Mambetova M. M. Kassenova Zh. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(4):880-882
Russian Journal of Physical Chemistry A - Cobalt-containing catalysts are studied via BET, XRD, SEM, and TPR-H2. Their activity in the reaction of carbon dioxide methane conversion and the process... 相似文献
17.
Ni/ZrO2催化剂上甲烷水蒸气重整反应的研究 总被引:4,自引:2,他引:4
研究了Ni/ZrO2催化剂对甲烷水蒸气重整制合成气的反应性能。考察了催化剂的还原温度、载体焙烧温度以及反应温度、原料配比和空速等对催化剂性能的影响。利用XRD、TEM、XPS等手段对催化剂的织构形貌进行了表征。研究表明,Ni/ZrO2催化剂用于甲烷水蒸气重整制合成气不仅具有较高的活性,也具有较好的稳定性。水蒸气比增加,CH4转化率增大、CO选择性下降。CH4转化率及CO选择性均随空速增大而下降。使用10%Ni/ZrO2催化剂,在650 ℃、空速1.984×104 h-1、原料气配比H2O∶CH4∶N2=2∶1∶2.67的条件下,获得CH4转化率85%、CO选择性70%的结果。 相似文献
18.
19.
甲烷在活性炭上裂解制氢研究 总被引:1,自引:4,他引:1
在连续流动石英固定床反应器上研究了甲烷在活性炭上裂解制氢的反应,并对反应前后活性炭的比表面积以及孔径分布等的变化进行了测定。结果表明,甲烷在五种活性炭上的裂解行为基本相同,反应初期转化率最高,随着反应进行转化率逐渐降低直至一个平稳的状态;降低甲烷分压和增加甲烷与活性炭的接触时间可提高甲烷转化率;温度的升高有利于初始转化率的提高,但不利于活性炭的稳定性;反应后活性炭比表面积、孔容及微孔孔容都明显降低,平均孔径增大,孔径分布向中孔方向迁移,说明甲烷的裂解导致了活性炭孔特别是微孔内的炭沉积以及进一步的孔堵塞。 相似文献