碳纳米管负载铂催化剂的制备、结构及电化学加氢特性

采用浸渍沉淀法制备Pt/CNTs和Pt/C催化剂,并对其结构及电催化性能进行比较,表征.实验表明,以碳纳米管作催化剂载体可使催化剂的负载量,载体上铂的分散度以及其活性中心大大提高.与Pt/C(JohnsonMatthey)催化剂相比,Pt/CNTs的电化学性能表现出更大的活性.碳纳米管作为阴极材料在质子交换膜燃料电池加氢反应器合成化学品中的作用十分明显.

丙烯醇在质子交换膜燃料电池反应器中的电化学加氢

利用质子交换膜燃料电池 (PEMFC)原理 ,设计了 PEMFC加氢反应系统装置 ,研究了 PEMFC加氢反应器中丙烯醇的电化学加氢。实验表明 ,丙烯醇能够在阴极转化为正丙醇 ,同时产生电能。并讨论了各种因素 (温度、浓度、反应物流量、催化剂载量等 )对丙烯醇加氢反应的影响。

1,3-二甲基-5-亚硝基-6-氨基脲嘧啶铂电极电化学加氢机理研究

采用稳态极化法、循环伏安法和恒电位库仑法对 1 ,3 -二甲基 -5 -亚硝基 -6-氨基脲嘧啶在铂电极上的电化学加氢机理进行了研究 ,研究介质为硫酸和硫酸钾水溶液 .结果表明 ,p H=3时 ,1 ,3 -二甲基 -5 -亚硝基 -6-氨基脲嘧啶在铂电极析氢电位 ( -60 0～ -80 0 m V,vs.饱和硫酸钾的硫酸亚汞参比电极 )前 ,发生加氢还原反应 ,氢离子在铂电极表面得到电子生成原子态的氢参与反应 .随着 p H值降低 ,加氢反应速度增大 ,还原电位正移 .在铂电极上的电化学加氢过程受扩散控制 。

有机物电化学加氢的研究进展

氢能作为一种绿色能源,对其安全储存及运输是实现其多场景应用的关键。通过有机物化学储氢的方式有希望实现常温常压下氢气的安全储运。本文阐述了通过电化学方法实现有机物加氢反应的研究现状,介绍了电化学加氢的反应机理,并讨论催化剂与载体间的界面作用、催化剂的分散状态对电化学加氢反应的影响规律,基于传统的电解液体系及其局限性,介绍了通过分离电解和加氢过程或构造非液相体系提升电化学加氢效率的方法,同时提出了有机物电化学加氢的发展趋势和方向。

1,3-二甲基-5-亚硝基-6-氨基脲嘧啶镍电极电化学加氢机理

采用稳态极化法、循环伏安法和恒电位库仑法研究了1,3-二甲基-5-亚硝基-6-氨基脲嘧啶(ANDMU)在镍电极上的电化学加氢机理,实验体系为pH 3的硫酸硫酸钾水溶液。结果表明,在镍电极析氢电位之前,在-0.7^-0.8 V(相对于Hg2SO4参比电极)ANDMU即发生加氢反应。随着pH值降低,还原电流增大,加氢反应速度增大,还原电位正移。反应受扩散控制,增大搅拌速度和提高温度都可以提高反应速度。ANDMU在镍电极上的电化学加氢反应机理与在铂电极上的情况相似,都是溶液中氢离子在电极表面得电子生成原子态氢还原ANDMU的EC(电化学反应后耦联有化学反应)过程。

加氢热化学处理对Super－α2合金中O相形成及形态的影响

利用ＳＥＭ，ＸＲＤ，ＴＥＭ研究了加氢热化学处理条件下Ｓｕｐｅｒ－ａ２合会的组织变化规律，探讨了合金中Ｏ相的形成以及Ｏ相形态、分布、数量与氢含量的关系。结果表明：氢的加入不仅明显地调整和细化组织及形态，同时促进了Ｏ相的形成。研究发现，Ｓｕｐｅｒ－ａ２台主中的Ｏ相由基体Ｂａ相中析出，二者之间具有特定的位相关系。

乙炔选择性加氢催化剂研究进展

乙烯是石化工业中最重要的工业原料之一,然而乙烯产品中少量乙炔杂质的存在会直接影响乙烯的下一步应用。乙炔选择性催化加氢被认为是脱除乙炔杂质最有效的方法之一。本文综述了乙炔选择性加氢催化剂近年来的研究进展,介绍了乙炔选择加氢的反应机理,归纳总结了活性组分、助剂、载体以及结构对乙炔加氢催化剂性能的影响。鉴于Pd基催化剂仍然是工业应用的主流催化剂,文中综述了Pd基催化剂的研究现状和目前存在的一些挑战,同时提出了催化性能优化的建议。最后,就如何进一步提高乙炔选择性加氢催化剂性能的发展趋势进行了归纳,主要从单原子合金催化剂、催化剂微观调控以及电化学炔烃加氢方面进行论述,为未来提高乙炔加氢催化剂的性能提供了指导方向。

异麦芽酮糖醇的生理活性及生物合成研究进展

异麦芽酮糖(又称“帕拉金糖”)是由1分子葡萄糖和1分子果糖以α-1,6糖苷键连接形成的还原型二糖,将异麦芽酮糖氢化还原后可以制得异麦芽酮糖醇(又称“帕拉金糖醇”),是国际上新兴的功能性食用糖醇。异麦芽酮糖醇是1种包含2种立体异构体即α-D-吡喃葡萄糖基-(1,6)-D-山梨醇(GPS)和α-D-吡喃葡萄糖基-(1,1)-D-甘露醇二水合物(GPM)的白色晶状混合物。根据GPS和GPM比例的不同,主要有ISOMALT ST、ISOMALT GS、ISOMALT DC和ISOMALT LM 4种不同的产品。异麦芽酮糖醇是迄今为止唯一完全由蔗糖衍生获得的二元糖醇,其口感近似于蔗糖,甜度约为蔗糖的45%,热值为蔗糖的50%,具有化学性质稳定、不致龋齿、摄取后不会导致血糖和胰岛素水平波动等优点,可以作为蔗糖的健康替代品。对异麦芽酮糖醇的生理功能、工业制造及应用现状进行了梳理,系统介绍了异麦芽酮糖醇的制造工艺路线(生物催化法和加氢还原技术),并重点介绍了异麦芽酮糖醇生物合成过程的关键酶——蔗糖异构酶的结构、催化机理和分子改造等方面的研究进展,以期为相关研究工作的开展和工业化生产提供指导。

木糖醇的生产工艺进展

主要综述了木糖醇的化学法和发酵法两种生产工艺。在工业生产中,主要以化学酸化催化加氢法生产木糖醇。生物发酵法的研究方向很多,但大多数还处于实验室阶段,未实现工业化生产。

Pd/ZnO catalysts with different origins for high chemoselectivity in acetylene semi-hydrogenation

The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective transformations. In this work, a Pd1/ZnO catalyst with single‐atom dispersion of Pd active sites was achieved by decreasing the Pd loading and reducing the sample at a relatively low temperature. The Pd1/ZnO SAC exhibited excellent catalytic performance in the chemoselective hydrogenation of acetylene with comparable chemoselectivity to that of PdZn intermetallic catalysts and a greatly enhanced utilization of Pd metal. Such unusual behaviors of the Pd1/ZnO SAC in acetylene semi‐hydrogenation were ascribed to the high‐valent single Pd active sites, which could promote electrostatic interactions with acetylene but restrain undesired ethylene hydrogenation via the spatial restrictions of σ‐chemical bonding toward ethylene.

Development and Application of DCC Catalysts to Meet New Demands

The new generation of DCC catalysts, the DMMC/RMMC series catalysts developed by RIPP are introduced in this paper. The large molecule cracking ability is enhanced by increasing the portion of large pores; and the coke selectivity is improved by adjusting the acidity site density on the matrix surface, while the selective cracking reactions are increased. The sphericity of catalysts is improved by adopting new preparation method. The commercial application results have shown that applying DMMC/RMMC series catalysts with the mixed VGO, VGO plus AR, and hydrotreated VGO feed can increase the propylene yield by 2.43, 1.3 and 0.8 percentage points, respectively, as compared to the previous catalysts along with improvement in some products yields. The refining enterprises can make more profits after applying new series of DCC catalysts.

Development and Commercial Application of Third Generation Resid Hydrotreating Catalysts

Based on the mechanism of resid hydrotreating reaction by coordinating the catalyst activity and stability, the diffusion mechanism and catalyst reactivity, the cost and catalyst performance, and the production and application requirements, the third-generation series catalysts for residue hydrotreating have been developed by Research Institute of Petroleum Processing, SINOPEC. The new series RHT catalysts possess higher activity for HDS, HDM and HDCCR performance as well as longer run length. The commercial results for application of these catalysts have demonstrated that the new catalyst system performs better than the reference ones.

Hydrodesulfurization activities of NiMo catalysts supported on mechanochemically prepared Al-Ce mixed oxides

Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3-CeO2 components in catalysts by impregnation method.The physicochemical properties of the catalysts were determined using chemical analysis,X-ray diffraction,temperature-programmed H2 reduction,temperature-programmed NH3 desorption,X-ray photoelectron spectroscopy（XPS）,and the Brunauer-Emmett-Teller method.The catalyst acidity decreased with increasing Ce concentration in the support.XPS showed that the NiS/MoS ratio decreased two-fold for the Ce-modified alumina support.NiMo6/Al2O3,which had the highest acidity,showed the highest activity in hydrodesulfurization of 1-benzothiophene（normalized per weight of catalyst）.The concentration of surface MoOxSy species（which is equal to the concentration of Mo^（5＋）） gradually decreased to zero for catalysts with Ce concentrations 10 wt%.However,the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3-CeO2supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.

Application of Discrete Lumped Kinetic Modeling on Vacuum Gas Oil Hydrocracking

The kinetic model of vacuum gas oil （VGO） hydrocracking based on discrete lumped approach was investigated, and some improvement was put forward at the same time in this article. A parallel reaction scheme to describe the conver- sion of VGO into products （gases, gasoline, and diesel） proposed by Orochko was used. The different experimental data were analyzed statistically and then the product distribution and kinetic parameters were simulated by available data. Fur- thermore, the kinetic parameters were correlated based on the feed property, reaction temperature, and catalyst activity. An optimization code in Matlab 2011b was written to fine-me these parameters. The model had a favorable ability to predict the product distribution and there was a good agreement between the model predictions and experiment data. Hence, the ki- netic parameters indeed had something to do with feed properties, reaction temperature and catalyst activity.

Reaction kinetics and phase behavior in the chemoselective hydrogenation of 3‐nitrostyrene over Co‐N‐C single‐atom catalyst in compressed CO_(2)

Single‐atom catalysts(SACs)have demonstrated excellent performances in chemoselective hydrogenation reactions.However,the employment of precious metals and/or organic solvents compromises their sustainability.Herein,we for the first time report the chemoselective hydrogenation of 3‐nitrostyrene over noble‐metal‐free Co‐N‐C SAC in green solvent—compressed CO2.An interesting inverted V‐curve relation is observed between the catalytic activity and CO2 pressure,where the conversion of 3‐nitrostyrene reaches the maximum of 100%at 5.0 MPa CO2(total pressure of 8.1 MPa).Meanwhile,the selectivities to 3‐vinylaniline at all pressures remain high(>99%).Phase behavior studies reveal that,in sharp contrast with the single phase which is formed at total pressure above 10.8 MPa,bi‐phase composed of CO2/H_(2)gas‐rich phase and CO2‐expanded substrate liquid phase forms at total pressure of 8.1 MPa,which dramatically changes the reaction kinetics of the catalytic system.The reaction order with respect to H_(2)pressure decreases from~0.5 to zero at total pressure of 8.1 MPa,suggesting the dissolved CO2 in 3‐nitrostyrene greatly promotes the dissolution of H_(2)in the substrate,which is responsible for the high catalytic activity at the peak of the inverted V‐curve.

MIL-53(Al)derived single-atom Rh catalyst for the selective hydrogenation of m-chloronitrobenzene into m-chloroaniline

The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation poses a significant challenge,which requires the rational design of the catalysts with proper hydrogenation ability for nitro group and simultaneously preventing dehalogenation of halogen group.Herein,a highly effective Rh@Al_(2)O_(3)@C single-atom catalyst(SAC)was developed for the hydrogenation of m-chloronitrobenzene(m-CNB)to m-chloroaniline(m-CAN),through an in-situ grafting of metal during the assembly of MIL-53(Al),followed by confined pyrolysis.Extensive characterizations reveal an exquisite structure of the Rh@Al_(2)O_(3)@C,containing atomically dispersed Rh sites onto Al_(2)O_(3) confined by the amorphous carbon.The five-coordinated aluminum(Al^(Ⅴ))species are essential for achieving the atomic dispersion of Rh atoms,providing the unsaturated coordinative sites for metal.Compared to the benchmark Rh/γ-Al_(2)O_(3) and Rh/C nanocatalysts,the Rh@Al_(2)O_(3)@C SAC affords an excellent turnover frequency of 2317 molm-CNB·molRh^(–1)·h^(–1),the highest value to date in heterogeneous catalyst systems for the hydrogenation of m-CNB at 313 K and 20 bar H2,together with a sustained selectivity to m-CAN(~98%)during five consecutive runs.The superior catalytic performance of the Rh@Al_(2)O_(3)@C is attributed to a proper modulation of electronic structure of hydrogenation metal by forming SAC,together with an enhanced accessibility of acid function sites.

Multiple Confined-Zone-Based Nickel Hydrogenation Catalyst Made by Shanxi Institute of Coal Chemistry

The Shanxi Institute of Coal Chemistry,Chinese Academy of Sciences has designed and prepared a multiple confined-zone-based nickel hydrogenation catalyst by means of the atomic layer deposition(ALD)technology.In comparison with the non-confined-zone based catalyst,the multiple confined-zone-based nickel catalyst possesses an enhanced catalytic reactivity and catalytic stability for hydrogenation of cinnamaldehyde and nitrobenzene.

Methanol as hydrogen source: Chemoselective transfer hydrogenation of α,β-unsaturated ketones with a rhodacycle

Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes highly chemoselective hydrogenation of α,β-unsaturated ketones with methanol as the hydrogen source. A wide variety of chalcones, styryl methyl ketones and vinyl methyl ketones, including sterically demanding ones, were reduced to the saturated ketones in refluxing methanol in a short reaction time, with no need for inter gas protection, and no reduction of the carbonyl moieties was observed. The catalysis described provides a practically easy and operationally safe method for the reduction of olefinic bonds in α,β-unsaturated ketone compounds.

Benzene selective hydrogenation over supported Ni(nano-) particles catalysts: Catalytic and kinetics studies

This report aims to reduce the benzene in a mixture of benzene and toluene as a model reaction using catalytic hydrogenation. In this research, we developed a series of catalysts with different supports such as Ni/HMS, Ni/HZSM-5, Ni/HZSM5-HMS, Ni/Al2O3 and Ni/SiO2. Kinetic of this reaction was investigated under various hydrogen and benzene pressures. For more study, two kinetic models have also been selected and tested to describe the kinetics for this reaction. Both used models, the power law and Langmuir-Hinshelwood, provided a good fit toward the experimental data and allowed to determine the kinetic parameters. Among these catalysts, Ni/Al2O3 showed the maximum benzene conversion （99.19%） at 130℃ for benzene hydrogenation. The lowest toluene conversion was observed for Ni/SiO2. Furthermore, this catalyst presented high selectivity to benzene （75.26%） at 130℃. The catalytic performance （activity, selectivity and stability） and kinetics evaluations were shown that the Ni/SiO2 is an effective catalyst to hydrogenate benzene. It seems that the surface properties particularly pore size are effective parameter compared to other factors such as acidity and metal dispersion in this process.

Development of RSDS-III Technology for Ultra-Low-Sulfur Gasoline Production

The 3rd generation catalytic cracking naphtha selective hydrodesulfurization(RSDS-III) technology developed by RIPP included the catalysts selective adjusting(RSAT) technology, the development of new catalysts and optimized process conditions. The pilot plant test results showed that the RSDS-III technology could be adapted to different feedstocks. The sulfur content dropped from 600 μg/g and 631 μg/g to 7 μg/g and 9 μg/g, respectively, by RSDS-III technology when feed A and feed B were processed to meet China national V gasoline standard, with the RON loss of products equating to 0.9 units and 1.0 unit, respectively. While the feed C with a medium sulfur content was processed according to the full-range naphtha hydrotreating technology, the sulfur content dropped from 357 μg/g in the feed to 10 μg/g in gasoline, with the RON loss of product decreased by only 0.6 units. Thanks to the high HDS activity and good selectivity of RSDS-III technology, the ultra-low-sulfur gasoline meeting China V standard could be produced by the RSDS-III technology with little RON loss.