羰基化石墨片催化丙烷氧化脱氢制丙烯

以资源丰富的石墨片为原材料, 通过简单的气相氧化处理制得羰基化石墨片, 并发现羰基化石墨片可以高选择性催化丙烷氧化脱氢制丙烯: 当丙烷转化率为12.4%时, 丙烯的选择性高达73.9%, 且副产物乙烯的选择性为13%。羰基化石墨片优良的烯烃选择性远超利用相同气相氧化处理的碳管, 并且可以媲美目前催化性能最优的六方氮化硼材料。催化剂具有良好的稳定性, 在505 ℃的反应温度下, 经过48 h的氧化脱氢反应测试后, 催化剂性能无明显的衰减。多种表征技术表明: 气相氧化处理不会破坏石墨片的结构, 且保留了石墨自身的高温抗氧化性, 而经过气相氧化处理羰基官能团的比例大幅度提高, 羰基作为活性位与丙烷中的氢原子发生反应, 自身形成羟基而丙烷则转换为丙烯, 羟基在高温下与氧原子反应生成为羰基, 从而完成催化剂的重生, 继续下一个循环。这种发生在催化剂表面的可控催化方式, 保证了丙烷氧化脱氢过程中选择性生成丙烯, 避免了深度氧化。另外, 石墨材料的来源广泛, 成本低, 作为催化剂可以极大地推动丙烷氧化脱氢的工业化。     

氧化钴/高炉渣催化剂的丙烷氧化脱氢性能

以攀钢高炉渣为载体,采用固体研磨法负载氧化钴,制备了氧化钴/高炉渣负载型催化剂,并以XRD、 H2-TPR技术对催化剂进行表征,研究了其对丙烷氧化脱氢制丙烯反应的催化性能.实验结果表明氧化钴负载在高炉渣上提高了丙烯选择性,氧化钴的负载量为20%时催化剂表现较好的催化性能,在550℃时丙烷转化率为28.80%,丙烯选择性为35.51%.本实验为资源综合利用及减少环境污染提供了新方法.     

平炉尘合成超细铁氧体催化性能研究

平炉尘提纯得到超细Fe2O3, 利用同晶型间的拓扑转化原理, 使平炉尘转化为超细铁氧体MnFe2O4、CoFe2O4催化剂, 并对催化剂进行了BET、XRD、H2-TPR、TEM和电导技术表征, 研究了其对丙烷氧化脱氢制丙烯反应的催化性能.实验结果表明由平炉尘转化得到的超细铁氧体CoFe2O4为p型半导体催化剂,对丙烷氧化脱氢制丙烯反应表现出优异的催化性能,当丙烷转化率在10%和20%时,丙烯的选择性分别为40.34%和35.23%.为资源综合利用及减少环境污染提供了新方法.     

钒基催化剂上丙烷氧化脱氢催化性能研究进展

低碳烷烃作为一种资源丰富且廉价的原料,利用其可制取具有高附加值的烯烃和含氧衍生物,对缓解丙烯和石油资源短缺具有重要的价值。但丙烷在高温下易深度氧化和深度裂解,且催化剂易积碳失活,使得丙烯选择性降低,故迫切需要开发低温高效的催化剂。简要介绍了丙烷氧化脱氢制丙烯的研究意义和钒基催化剂上丙烷氧化脱氢反应的机理,综述了负载型钒基催化剂的载体类型及性质、活性物种引入方式、表面钒物种的还原性能、钒负载量、氧化剂的选择对丙烷氧化脱氢催化活性及对丙烯选择性的影响。     

孤立Pt位点于Pt-Sn、Pt-Zn配位的PtSnZn有序金属间化合物选择性催化丙烷脱氢（英文）

随着页岩气的大规模开采,丙烷脱氢制丙烯日益重要.在本文中我们以Al₂O ₃为载体,结合强静电吸附法和程序升温还原法合成了～0.9 nm PtSnZn有序金属间化合物团簇(PtSnZn/Al₂O₃).PtSnZn金属间化合物的结构形成主要受动力学控制,Pt原子被Sn和Zn完全孤立,形成Pt-Sn和Pt-Zn原子对.PtSnZn/Al₂O₃在丙烷脱氢反应中表现出优异的催化性能,丙烯选择性高达～100%,并且在长周期稳定性测试中丙烷转化率维持在40%以上.Pt Sn Zn/Al₂O ₃的丙烷脱氢催化性能远远优于Pt/Al₂O₃、PtSn/Al₂O₃和PtZn/Al₂O₃催化剂.实验结果和理论计算表明Sn 5p和Zn 4s与Pt 5d轨道的杂化使得Pt d带中心远离费米能级(-2.81 eV...     

生物质碳基催化材料的研究进展

生物质是产量丰富、种类繁多、价格低廉、环境友好的优良碳源,以生物质为原料制备碳催化材料无疑是变废为宝,可从根本上解决环境污染和资源浪费等问题。介绍了生物质的种类、组分及结构对生物质碳基催化材料性能的影响,对制备生物质碳基催化材料的两种常见方法热解法和水热碳化法进行了对比,探讨了进一步增强催化剂活性的3种方式：杂原子掺杂、金属离子修饰和官能化,分析总结了生物质碳催化材料面临的挑战。     

CH3COONa处理HZSM-5分子筛及其催化性能

采用不同浓度的CH₃COONa溶液和常规碱(NaOH和Na₂CO₃)溶液处理HZSM-5分子筛, 对处理前后的HZSM-5分子筛负载Pt, 制备Pt/HZSM-5催化剂用于丙烷脱氢反应。利用X射线衍射(XRD)、X射线荧光光谱(XRF)、扫描电镜(SEM)、比表面测试仪(BET)、NH₃-TPD(程序升温脱附法)和H₂化学吸附等手段对处理前后的HZSM-5分子筛进行表征, 并考察了不同浓度的CH₃COONa溶液和常规碱溶液处理对HZSM-5分子筛的晶体结构、表面形貌、孔结构、表面酸性及丙烷脱氢性能的影响。结果表明, CH₃COONa溶液具有碱改性作用, 与常规碱溶液相比, 采用CH₃COONa溶液处理HZSM-5分子筛, 能够在对分子筛的晶体结构和表面形貌影响较小的基础上有效地引入介孔结构, 具有较好的可调控性; 随着CH₃COONa溶液浓度的增加, 丙烷脱氢反应的丙烷初始转化率和丙烯选择性先升高后降低, 当CH₃COONa溶液浓度为4.0 mol/L时, 丙烷初始转化率和丙烯选择性均达到最高值, 分别为34.5%和98.9%。     

焦钒酸镍的X射线光电子能谱及其氧化脱氢催化性能研究

采用微波草酸盐共沉淀法制备了焦钒酸镍Ni2V2O7催化剂,并用XRD、BET、H2-TPR、XPS、TEM和电导等技术表征.研究了Ni2V2O7催化剂的丙烷氧化脱氢(ODH)制丙烯催化性能与其表面物种的关系.TPR和XPS实验结果显示p型半导体焦钒酸镍Ni2V2O7催化剂中,晶格氧可以较容易转换成未完全还原氧,使催化剂内各种价态的钒之间易于进行氧化还原反应并形成氧缺位,从而催化剂的表面含有较多未充分还原氧物种O-和V4 物种.从而使其具有较高的丙烯选择性.     

钌基催化剂的制备及其析氢性能的研究

电化学水分解制氢是一种极具发展前景的无污染制氢方法。设计一种价格低廉,并且具有高效催化性能的催化剂对缓解环境压力,以及对电催化析氢的大规模应用具有重要意义。以松果壳(PC)为生物质碳前驱体,尿素为氮源,RuCl₃为钌源,通过水热和高温碳化的方法将Ru锚定在氮掺杂的生物质衍生碳基底上(Ru-N-CPC)。Ru-N-CPC具有良好的电化学性能(61 mV的过电位就可达到10 mA cm^-2,1 mol/L KOH)和稳定性。采用一系列测试表明催化剂具有良好的电化学性能可归因于氮的掺杂导致了大量的缺陷产生,从而使Ru能够顺利地、均匀地被载于碳材料上,同时由于Ru和N的协同作用,促使催化析氢反应的活性提高。     

无溶剂合成以Co-N物种为活性位点的Co@NC催化剂用于芳香硝基化合物选择加氢（英文）

金属有机骨架(MOFs)衍生的Co基催化剂用于芳香硝基化合物选择加氢引起了广泛的关注,但催化剂合成过程中使用大量溶剂,且对催化剂中活性中心的认识存在争议.本文开发了一种固相合成策略,在不使用任何溶剂的情况下获得MOF前体材料,经发泡和热解处理获得Co@NC催化剂.研究发现, 800°C热解所得的催化剂中Co纳米颗粒被氮掺杂石墨烯壳层包裹,在3-硝基苯乙烯的加氢过程中表现出～100%的转化率, 3-乙烯基苯胺的选择性大于99%,同时,该催化剂具有良好的循环稳定性和底物普适性.表征和实验结果证明该催化剂中Co–N物种为活性中心,其含量可通过热解温度进行调变,且催化性能与Co–N物种的含量存在正相关关系.本工作为设计用于选择加氢反应的高效Co基催化剂提供了一种新的绿色合成策略.     

Comparative study of propane oxidative dehydrogenation in fluidized and fixed bed reactor

Supported vanadia catalyst was successfully synthesized using wet impregnation of γ-alumina to study propane oxidative dehydrogenation (POD). The prepared catalysts were characterized with X-ray diffraction and BET tests. To investigate performance of fluidized bed reactor in comparison to fixed bed micro-reactor, propane conversion and propylene selectivity were measured in temperatures of 480 to 550°C and GHSV of 48000, 60000, and 78000 cc/gr.hr at equimolar feed ratio of propane to oxygen. The results indicated that at constant temperature propane conversion obtained in the fixed bed reactor was higher. But fluidized bed is superior to fixed bed reactor in terms of propylene selectivity leading to considerably higher propylene yields over the fixed bed. It is suggested that pre-filtering effect induced by hydrodynamics of fluidized bed reactor has major effect in the enhancement of propylene selectivity beyond that of fixed bed micro-reactor.     

Membrane reactor microstructure for polymer grade olefin production and hydrogen cogeneration

The current communication describes research work on effective membrane reactor nanostructures and nanoreaction-nanoseparation technology for polymer grade olefin production via catalytic paraffin dehydrogenation reactions. Emphasis is given in systems of permreactors and permeators to perform the described reactive and separative operations. We elaborate on new membrane microstructure designs for paraffin dehydrogenations including the design of experiments, operation, and best parameter selection and optimization of such systems. The described processes are of current significance in the area of new microreactor design and operation including hydrocarbon processing and conversion to valuable fuels and chemicals such as hydrogen, olefins, and polyolefins. These improved results are because of the unique design characteristics of the examined microreactor systems to perform accurate multiphase and heterogeneous functions into one unit operation. A number of membrane reactor configurations were made and tested on stream for the catalytic propane dehydrogenation reaction to propylene with successful results. Some of the results are discussed below which show the better performance of nanostructured membrane reactors for the specific dehydrogenation.     

New approach for enhancement of light olefin production through oxidative dehydrogenation of propane over doped Mo/TiO2 nanotubes

Using promoters in different types of catalysts can positively affect the yield of oxidative dehydrogenation process and the selectivity of propylene as the main product Titania nanotubes containing distinct promoters including silver, nitrogen and cerium have been synthesized with high specific area by the hydrothermal technique and used as a support in oxidative dehydrogenation of propane. The incipient wetness impregnation method was applied for catalysts preparation Mo/Ce-TNT, Mo/Ag-TNT and Mo/N-TNT were characterized by various techniques such as XRD, TEM, SEM, EDS, BET, H₂-TPR. The presence of these promoters lead to enhancement of propylene yield among which the Mo/Ce-TNT catalyst was of great efficiency. From the results, it is considered to be quite evident that the oxygen capacity of the catalyst containing Ce can contribute to the oxidation state and redox reactions. In comparison to Mo/TNT, the yield to propylene in the Mo/Ce-TNT sample increased from 9.3% to 14.8% and propylene selectivity substantially surged from 39% to 66.3%.     

非贵金属/碳氮复合材料电催化析氧反应的研究进展

析氧反应(OER)是一种复杂的四电子转移反应,其动力学缓慢、所需能量高,制约了电解水制氢等新型能源技术的发展.近年来,非贵金属复合材料因其优异的催化活性以及相比于贵金属基催化剂的成本优势而受到广泛关注.本文概述了这一研究领域的最新进展,首先简要介绍析氧反应的机理以及材料催化性能的评价方法,重点关注非贵金属/碳氮复合材料...     

负载型MoO3／β分子筛催化剂的丙烷氧化脱氢性能

以β分子筛为载体,采用浸渍法负载钼制备了MoO3／β筛催化剂,通过XRD、FTIR、BET、NH3-TPD进行表征,结果表明,样品中有活性组分氧化钼存在,也有不同酸性质的活性位存在,负载量对催化剂的表面积和孔径有影响;考察了催化剂对丙烷氧化脱氢制丙烯的催化性能,结果表明,单纯β分子筛载体有催化活性,不同钼负载量对催化性能有影响,考察负载量区间内反应转化率出现极值。     

Conformation‐Controlled Molecular Sieving Effects for Membrane‐Based Propylene/Propane Separation

Membrane‐based separation is poised to reduce the operation cost of propylene/propane separation; however, identifying a suitable molecular sieve for membrane development is still an ongoing challenge. Here, the successful identification and use of a metal–organic framework (MOF) material as fillers, namely, the Zr‐fum‐ fcu ‐MOF possessing an optimal contracted triangular pore‐aperture driving the efficient diffusive separation of propylene from propane in mixed‐matrix membranes are reported. It is demonstrated that the fabricated hybrid membranes display a high propylene/propane separation performance, far beyond the current trade‐off limit of polymer membranes with excellent properties under industrial conditions. Most importantly, the mechanism behind the exceptional high propylene/propane selectivity is delineated by exploring theoretically the efficiency of sieving of different conformers of propane through the hypothesized triangular rigid pore‐aperture of Zr‐fum‐ fcu ‐MOF.