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Effect of manganese on the catalytic performance of an iron-manganese bimetallic catalyst for light olefin synthesis

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Journal of Energy Chemistry 2013年第4期22卷 624-632页

作者： Tingzhen Li Hulin Wang Yong Yang Hongwei Xiang Yongwang Li State Key Laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of Sciences College of Chemistry and Environmental Engineering Chongqing Three Gorges University Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education Southeast University

A systematic study was carried out to investigate the promotion effect of manganese on the performance of a coprecipitated iron-manganese bimetallic catalyst for the light olefins synthesis from syngas. The catalyst samples were characterized by N2 physisorption, transmis- sion electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS）, powder X-ray diffraction （XRD）, Mossbauer spectroscopy, H2- differential thermogravimetric analysis （H2-DTG）, CO temperature-programmed reduction （CO-TPR） and CO2 temperature-programmed des- orption （CO2-TPD）. The Fischer-Tropsch synthesis （FTS） performance of the catalyst was measured at 1.5 MPa, 250 ℃ and syngas with H2/CO ratio of 2.0. The characterization results indicated that the addition of manganese decreases the catalyst crystallite size, and improves the catalyst BET surface area and pore volume. The presence of manganese suppresses the catalyst reduction and carburization in H2, CO and syngas, respectively. The addition of manganese improves the catalytic activity of water-gas shift reaction and suppresses the oxidation of iron carbides in the FTS reaction. The incorporation of manganese improves the catalyst surface basicity and results in a significant improvement in the selectivities to light olefins and heavy hydrocarbons （C5＋）, and furthermore an inhibition of methane formation in FTS. The pure iron catalyst （Mn-00） has the highest initial FTS catalytic activity （65%） and the lowest selectivity （17.35 wt%） to light olefins （C2=-C4=）. The addition of an appropriate amount of manganese can improve the catalyst FTS activity.

关键词： light olefin Fischer-Tropsch synthesis iron-manganese bimetallic catalyst carburization

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Effect of Reduction and Carburization Pretreatment on Iron Catalyst for Synthesis of light olefins from CO Hydrogenation

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Chemical Research in Chinese Universities 2017年第4期33卷 672-677页

作者： AN Tong DANG Dan CHENG Yi Department of Chemical Engineering Tsinghua University Beijing 100084 P. R. China

Effect of reduction and carburization pretreatment on iron catalyst for CO hydrogenation to light olefins was investigated. The bulk structure and surface composition of the catalysts during pretreatment were characterized by means of X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS） and high-resolution transmission elec- tron microscopy（HRTEM）. The results indicated that phase transformation of iron phases involved a-Fe203---~Fe304 --,a-Fe both in the bulk and on the surface layers in hydrogen atmosphere. However, a-Fe203 was firstly transformed to Fe3C and then to Fe5C2 in CO atmosphere, while in syngas atmosphere directly to Fe5C2. As carburization pretreatment time was prolonged, the degree of carburization on the surface increased, and the increase degree of iron catalyst carburization in CO pretreatment was stronger than that in syngas pretreatment. It inferred that surface carbon species was more easily formed in syngas pretreatment instead of iron carbide in CO pretreatment. After hydrogen pretreatment, when the catalyst was reduced to a mixture of magnetite and metallic iron, the selectivity to light olefins was relatively low. Under the joint effects of the active sites from surface iron carbide and surface carbon layers blocking the active sites, longer CO pretreatment time resulted in higher methane selectivity and less light olefins. The selectivity to methane on H2-pretreated catalyst was lower than that of CO-pretreated catalyst.

关键词： light olefin Fischer-Tropsch synthesis CO hydrogenation Iron catalyst Pretreatment

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Review of Directly Producing light olefins via CO Hydrogenation

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Journal of Natural Gas Chemistry 2003年第1期12卷 10-16页

作者： Chong Wang, Longya Xu, Qingxia WangDalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China

Directly making light olefins via CO hydrogenation is a promising process toobtain a non-petroleum based supply of alkenes. Limited by the ASF distribution function ofFischer-Tropsch synthesis, the yield of light olefins (C_2-C_4) can not reach the desired levels,which is a great challenge to overcome. Beginning with a brief introduction of F-T synthesis, thispaper provides a review of current research, including thermodynamic analysis, the ASF distributionfunction, the reaction performance of CO hydrogenation and slurry reactor studies. The problemscurrently faced by this research area are presented at the end of the article.

关键词： light olefin fischer-tropsch synthesis iron based catalyst promoter CO hydrogenation

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Effects of zinc on Fe-based catalysts during the synthesis of light olefins from the Fischer-Tropsch process

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Chinese Journal of Catalysis 2016年第4期37卷 510-516页

作者：高新华张建利陈宁马清祥范素兵赵天生椿范立宁夏大学省部共建天然气转化国家重点实验室培育基地宁夏银川750021 日本富山大学工学部应用化学系

Fe‐based catalysts for the production of light olefins via the Fischer‐Tropsch synthesis were modi‐fied by adding a Zn promoter using both microwave‐hydrothermal and impregnation methods. The physicochemical properties of the resulting catalysts were determined by scanning electron mi‐croscopy, the Brunauer‐Emmett‐Teller method, X‐ray diffraction, H2 temperature‐programed re‐duction and X‐ray photoelectron spectroscopy. The results demonstrate that the addition of a Zn promoter improves both the light olefin selectivity over the catalyst and the catalyst stability. The catalysts prepared via the impregnation method, which contain greater quantities of surface ZnO, exhibit severe carbon deposition following activity trials. In contrast, those materials synthesized using the microwave‐hydrothermal approach show improved dispersion of Zn and Fe phases and decreased carbon deposition, and so exhibit better CO conversion and stability.

关键词： Zn promoter Fe-based catalyst light olefin Fischer-Tropsch synthesis Microwave-hydrothermal method

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SYNTHESIS OF light olefinS FROM SYNGAS VIA DIMETHYLETHR——A NEW TECHNIQUE PROCESS

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Journal of Energy Chemistry 1995年第2期 148-156页

作者： CAI Guang-Yu LlU Zhong-Min SHI Ren-Min HE Chang-Qing YANG Li-Xin SUN Cheng-LinDalian Institute of Chemical Physics, Acadernia Sinica Dalian, Iiaorting 116023

A new route named as SDTO method for the synthesis of lightolefins from syngas has been *** is to convert syngas todimethylether and then to convert dimethylether to light *** catalystsfor the two conversion reactions have been *** the first reaction,the catulySt was synthesized by the combination of methanol synthesis catalystwith γ-AlOor zeolites which possesses both metallic and acidic *** for the second reaction was modified SAPO-34 molecular *** of the reactions have also been *** results from theserial connection of the two conversion steps without any separation show thatthe yield of CColefins Could be>100g/（msyngas）.

关键词： light olefin syngas dimethylether SAPO-34

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Improving circulating fluidized bed dehydrogenation technology through optimization of fluidization

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Particuology 2020年第3期18卷 127-134页

作者： Mayank Kashyap Malleswara Rao Tadiboyina Christian Okolo Sami Al-Mutairi SABIC Technology and Innovation SABIC14100 Southwest FreewaySuite 600Sugar LandTexas 77478USA SABIC Technology Management SABICUrmonderbaan 22/6167 RdGeleenNetherlands SABIC Technology Management SABICJubail Industrial CityJubail31961Saudi Arabia

The dehydrogenation of light alkanes to corresponding light olefins is an important industrial *** present work involved the assessment of a commercial alkane dehydrogenation circulating fluidized bed (CFB) reactor unit that had been underperforming and exhibiting higher than expected catalyst losses over a long period of *** aspects of this unit related to fluidization,catalysis,and process engineering were investigated to understand and resolve these *** primary focus was on the fluidization aspects of the process,along with a comparison of equipment design and operating conditions to accepted best practices in the *** designs of key equipment in the reactor and regenerator,including feed distributors,fuel gas distributors,cyclones,baffles,strippers,transfer lines,risers,riser terminations,and refractories,were studied in *** attrition rates of different types of catalysts used in the unit were also *** recommendations and improvement opportunities were proposed to significantly increase light olefins production and reduce catalyst losses,and were accepted and *** study provides insights into means of improving fluidization behavior and highlights the viability of employing a systematic approach to determine the underlying root causes of issues in a commercial CFB reactor unit.

关键词： Fluidization Circulating fluidized bed Dehydrogenation light olefin Catalyst loss

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Core-shell-structured Composite ZSM-5@MCM-41 Catalysts:Fabrication,Characterization,and Enhanced Performance in Hexane Catalytic Cracking

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China Petroleum Processing & Petrochemical Technology 2023年第4期25卷 41-51页

作者： Zhu Jiale Zhu Xuedong Yang Fan State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science&TechnologyShanghai 200237China

A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an ultradilute solution. Extensive characterization techniques, including XRD, TEM, N_(2) adsorption-desorption, NH_(3)-TPD, and IR measurements, confirmed the successful coating of a microporous ZSM-5 core with a mesoporous MCM-41 shell layer and were further employed to explore the textural properties and acidic properties of the samples. The hexane cracking results revealed a significant enhancement in olefin yields after introducing the MCM-41 shell to ZSM-5. Interestingly, a volcanic trend in olefin yields was observed with the increase in the shell thickness. In particular, the highest olefin yield of 51.5%, exceeding that of the core catalyst by 17.1%, was achieved when the shell thickness was controlled at 40 ***, the catalyst lifetime investigation revealed that the core-shell composite catalyst exhibited a minimal reduction in hexane conversion of merely 3.8% over a 120 h reaction period, significantly outperforming the 11.3% reduction exhibited by the core catalyst. This remarkable catalytic performance was attributed to the passivation of external acid sites and the introduction of more developed pore channels by the shell, which effectively mitigated unwanted side reactions. The successful synthesis of these core-shell structured catalysts presents a novel strategy for improving catalytic performance in hexane cracking, in addition to serving as a solid foundation for the design of industrial catalysts for light naphtha cracking.

关键词： catalytic cracking light olefin core-shell ZSM-5 zeolite

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Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

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Journal of Materials Science and Chemical Engineering 2021年第7期9卷 10-27页

作者： Yuhao Cen Fan Yang Xuedong Zhu Kake Zhu Engineering Research Center of Large-Scale Reactor Engineering and Technology Ministry of Education East China University of Science and Technology Shanghai China

Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600°C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.

关键词： Catalytic Cracking light olefin MFI Zeolite Titanium

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