In Situ IR Spectroscopic Study on the Hydrogenation of 1,3-Butadiene on Fresh Mo_2C/γ-Al_2O_3 Catalyst

The surface species formed from the adsorption of 1,3-butadiene and 1,3-butadiene hydrogenation over the fresh Mo2C/γ-Al2O3 catalyst was studied by in situ IR spectroscopy. It is found that 1,3-butadiene adsorption on the Mo2C/γ-Al2O3 catalyst mainly forms π-adsorbed butadiene(πs and πd) and σ-bonded surface species. These species are adsorbed mainly on the surface Moδ+(0<δ<2) sites as evidenced by co-adsorption of 1,3-butadiene and CO on the fresh Mo2C/γ-Al2O3 catalyst. The IR spectrometric analysis show that hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst produces mainly butane coupled with a small portion of butene. The selectivity of butene during the hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst might be explained by the adsorption mode of adsorbed 1,3-butadiene. Additionally, the active sites of the fresh Mo2C/γ-Al2O3 catalyst may be covered by coke during the hydrogenation reaction of 1,3-butadiene. The treatment with hydrogen at 673 K cannot remove the coke deposits from the surface of the Mo2C/γ-Al2O3 catalyst.

Selective hydrogenation of 1,3-butadiene on iridium nanostructures:Structure sensitivity, host effect, and deactivation mechanism

A systematic study on the structure sensitivity,host effect,and the deactivation mechanism of Ircatalyzed selective hydrogenation of 1,3-butadiene,a key process in the purification of alkadiene for the upgrading of C4 cut,is presented by coupling steady-state catalytic testing,in-depth characterization,kinetic evaluation,and density functional theory calculations.We reveal that:(i) 1,3-Butadiene hydrogenation on iridium is structure-sensitive with the optimal particle size of about 2 nm,and the H_(2) dissociation energy is a reliable activity descriptor;(ii) The nature of the NC hosts exerts a critical impact on the catalytic performance,and balanced nitrogen content and speciation seem key for the optimized performance;and (iii) Different deactivation mechanisms occur:fouling by coke deposition on the catalysts with a high N:C ratio (>1),and site blockage due to the competitive adsorption between 1-butene/cis-2-butene and 1,3-butadiene.These molecular insights provide valuable guidelines for the catalyst design in selective hydrogenations.

Palladium-catalyzed dicarbonylation of 1,3-butadiene with bidentate phosphine ligands:A density functional theory study

DFT calculations have been performed to discover the mechanism for the synthesis of dimethyl adipate(DMA)by 1,3-butadiene(BD)dicarbonylation catalyzed by a complex consisting of palladium and a bidentate diphosphine ligand.The computational results indicate that BD dicarbonylation involves two catalytic stages with the same reaction mechanism including terminal alkenyl insertion,CO migratory insertion,and methanolysis.Four different reaction routes have been explored,the pathway yielding linear DMA has the lowest alkenyl C-H insertion barrier with an overall barrier of 13.4 kcal·mol^(-1)(1 kcal·mol^(-1)=4.184 kJ·mol^(-1)).The regioselectivity of the BD dicarbonylation depends mainly on the barrier of the alkenyl insertion into the palladium-hydrogen complex site.The computations well reproduced the experimentally observed linear selectivity.

Highly active Cu/SiO_2 catalysts for hydrogenation of diethyl malonate to 1,3-propanediol

Cu/SiO2 catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3‐propanediol. The calcination temperature played an important role in the structural evolution and catalytic performance of the Cu/SiO2 catalysts, which were systematically characterized by N2 adsorption‐desorption, inductively coupled plasma‐atomic emission spectros‐copy, N2O chemisorption, X‐ray diffraction, Fourier transform infrared spectroscopy, H2 tempera‐ture‐programmed reduction, transmission electron microscopy, and X‐ray photoelectron spectros‐copy. When the Cu/SiO2 catalyst was calcined at 723 K, 90.7%conversion of diethyl malonate and 32.3%selectivity of 1,3‐propanediol were achieved. Compared with Cu/SiO2 catalysts calcined at other temperatures, the enhanced catalytic performance of the Cu/SiO2 catalyst calcined at 723 K can be attributed to better dispersion of copper species, larger cupreous surface area and greater amount of copper phyllosilicate, which results in a higher ratio of Cu＋/Cu0. The synergetic effect of Cu0 and Cu＋is suggested to be responsible for the optimum activity.

Numerical Investigation on 1,3-Butadiene/Propyne Co-pyrolysis and Insight into Synergistic Effect on Aromatic Hydrocarbon Formation

A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation. A detailed kinetic model of 1,3-butadiene/propyne co-pyrolysis with the sub-mechanism of aromatic hydrocarbon formation is developed and validated on previous 1,3-butadiene and propyne pyrolysis experiments. The model is able to reproduce both the single component pyrolysis and the co-pyrolysis experiments, as well as the synergistic effect between 1,3- butadiene and propyne on the formation of a series of aromatic hydrocarbons. Based on the rate of production and sensitivity analyses, key reaction pathways in the fuel decomposition and aromatic hydrocarbon formation processes are revealed and insight into the synergistic effect on aromatic hydrocarbon formation is also achieved. The synergistic effect results from the interaction between 1,3-butadiene and propyne. The easily happened chain initiation in the 1,3-butadiene decomposition provides an abundant radical pool for propyne to undergo the H-atom abstraction and produce propargyl radical which plays key roles in the formation of aromatic hydrocarbons. Besides, the 1,3-butadiene/propyne co-pyrolysis includes high concentration levels of C3 and C4 precursors simultaneously, which stimulates the formation of key aromatic hydrocarbons such as toluene and naphthalene.

Mechanistic insights into the selective hydrogenation of resorcinol to 1,3-cyclohexanedione over Pd/rGO catalyst through DFT calculation

In our previous work, graphene-supported Pd catalyst(Pd/rGO) exhibited higher activity and selectivity for the liquid phase selective hydrogenation of resorcinol to 1,3-cyclohexanedione compared with other catalysts. In the present study, further experimental and theoretical investigations were conducted to reveal the reaction mechanism and the catalytic mechanism of Pd/rGO for resorcinol hydrogenation. The effects of graphene nanosheet and the solvent on the reaction were investigated, and the pathway for resorcinol hydrogenation was proposed supported by density functional theory(DFT) calculations. The results showed that the excellent selectivity of Pd/rGO to 1,3-cyclohexanedione was attributed to the strong π–π and p–π interactions between the graphene nanosheet and the benzene ring as well as hydroxyl in resorcinol molecule, which was in agreement with our previous speculation. In weak polar aprotic solvents, solvation free energy had less impact to the π–π and p–π interactions mentioned above. In strong polar aprotic solvents and polar protic solvents,however, the influence of solvation free energy was much greater, which led to the decrease in the conversion of resorcinol and the selectivity to 1,3-cyclohexanedione.

Reaction Mechanism of One-Step Conversion of Ethanol to 1,3-Butadiene over Zn-Y/BEA and Superior Catalysts Screening

The one-step conversion of ethanol to 1,3-butadiene has achieved a breakthrough with the development of beta zeolite supported dual metal catalysts.However,the reaction mechanism from ethanol to butadiene is complex and has not yet been fully elucidated,and no catalyst screening effort has been done based on central metal atoms.In this work,density functional theory(DFT)calculations were employed to study the mechanism of one-step conversion of ethanol to butadiene over ZnY/BEA catalyst.The results show that ethanol dehydrogenation prefers to proceed on Zn site with a reaction energy of 0.77 eV in the rate-determining step,and the aldol condensation to produce butadiene prefers to proceed on Y site with a reaction energy of 0.69 eV in the rate-determining step.Based on the mechanism revealed,six elements were selected to replace Y for screening superior combination of Zn-M/BEA(M=Sn,Nb,Ta,Hf,Zr,Ti;BEA:beta polymorph A)for this reaction.As a result,Zn-Y/BEA(0.69 eV)is proven to be the most preferring catalyst compared with the other six ones,and Zn-Zr/BEA(0.85 eV),Zn-Ti/BEA(0.87 eV),and Zn-Sn/BEA(0.93 eV)can be potential candidates for the conversion of ethanol to butadiene.This work not only provides mechanistic insights into one-step catalytic conversion of ethanol to butadiene over Zn-Y/BEA catalyst but also offers more promising catalyst candidates for this reaction.

Synergistic effects of bimetallic Cu-Fe/SiO_2 nanocatalysts in selective hydrogenation of diethyl malonate to 1,3-propanediol

Cu-x-Fe-y/SiO2 catalysts were prepared using urea-assisted sol-gel method. The structure and physicochemical properties of the catalysts were characterized using N-2 adsorption-desorption, transmission electron microscopy, H-2-temperature-programmed reduction, powder X-ray diffraction, and X-ray photoelectron spectroscopy. Compared with monometallic Cu or Fe catalysts, the bimetallic Cu-x-Fe-y/SiO2 catalysts exhibited enhanced catalytic performance for the selective hydrogenation of diethyl malonate to 1,3-propanediol. The bimetallic catalyst with an optimal Cu/Fe atomic ratio of 2 exhibited the highest activity, which yielded 96.3% conversion to diethyl malonate and 93.3% selectivity to 1,3-propanediol under the optimal reaction conditions. Characterization results revealed that interactions between Cu and Fe contributed to the improvement of diethyl malonate conversion and selectivity to 1,3-propanediol. The X-ray photoelectron spectroscopy results revealed that the addition of appropriate amount of Fe species enhanced the reduction of Cu2+ species, thereby increasing the Cu-0 species on the surface of bimetallic catalyst. It led to a better chemisorption capacity of hydrogen and further promoted of the activation of hydrogen molecule. The ethyl acetate temperature-programmed desorption results indicated that the FeOx species provided the additional adsorption sites for substrate molecules, and they activated the C=O bond. The improved catalytic performance of bimetallic Cu-x-Fe-y/SiO2 catalyst was mainly attributed to the synergistic effect between Cu-0 and FeOx species. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Conversion of ethanol to 1,3-butadiene over Ag-ZrO_(2)/SiO_(2) catalysts:The role of surface interfaces

A series of Ag-ZrO_(2)/SiO_(2) catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity.According to the results of detailed characterizations(e.g.CO/pyridine-DRIFTS,XPS,TEM,NH3-TPD,and ^(1)H MAS NMR),it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO_(2) improved the interaction between Ag and ZrO_(2)/SiO_(2),creating more Ag^(δ+)active sites.The high dispersion of ZrO_(2) on SiO_(2) generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity,promoting the condensation of acetaldehyde to crotonaldehyde.These Zr-O-Si interfaces in close interaction with Ag^(δ+)species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol.The synergies among the interfaces resulted in retarded ethanol dehydration reactivity,balanced ethanol dehydrogenation and condensation reactions,and a subsequent high 1,3-butadiene yield.

Design strategies and structure‐performance relationships of heterogeneous catalysts for selective hydrogenation of 1,3‐butadiene

Selective hydrogenation of 1,3‐butadiene is an essential process in the upgrading of the crude C4 cut from the petroleum chemical sector.Catalyst design is crucial to achieve a virtually alkadiene‐free product while avoiding over‐hydrogenating valuable olefins.In addition to the great industrial relevance,this demanding selectivity pattern renders 1,3‐butadiene hydrogenation a widely used model reaction to discriminate selective hydrogenation catalysts in academia.Nonetheless,critical reviews on the catalyst development are extremely lacking in literature.In this review,we aim to provide the reader an in‐depth overview of different catalyst families,particularly the precious metal‐based monometallic catalysts(Pd,Pt,and Au),developed in the last half century.The emphasis is placed on the development of new strategies to design high‐performance architectures,the establishment of structure‐performance relationships,and the reaction and deactivation mechanisms.Thrilling directions for future optimization of catalyst formulations and engineering aspect are also provided.

3-羟基丙酸甲酯加氢合成1,3-丙二醇反应中La对Cu/SiO_(2)催化剂的修饰作用

[目的] 3-羟基丙酸酯加氢制备1,3-丙二醇(1,3-PDO)过程中存在β-羟基脱除等副反应,导致1,3-PDO的选择性和收率不高,其中高效催化剂的开发是解决该问题的关键.[方法]采用蒸氨法制备了不同添加量La修饰的20Cu/SiO_(2)催化剂,对其进行催化性能评价,并通过H_(2)程序升温还原(H_(2)-TPR)、X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和N_(2)物理吸附-脱附对其进行表征.[结果] 20Cu-0.50La/SiO_(2)的催化性能最佳,它显著地提高了3-羟基丙酸甲酯(3-HMP)加氢制1,3-PDO的催化活性和稳定性,其中3-HMP转化率为91.8%,1,3-PDO的选择性和收率分别为85.2%和78.2%.这是在高液时空速(LHSV=0.10 h^(-1))的条件下取得的最佳结果.[结论] La的加入与Cu产生了强相互作用,增强了催化剂中Cu的分散性,同时提高了Cu^(+)物种表面浓度,使活性Cu的比表面积增加,从而提高了加氢反应的活性和稳定性.

葛根粉中1,2-丙二醇和1,3-丙二醇的测定

目的:建立气相色谱-氢火焰离子化检测法(Gas Chromatography-Flame Ionization Detector,GC-FID)和气相色谱-质谱法(Gas Chromatography-Mass Spectrometry,GC-MS)同时检测葛根粉中1,2-丙二醇和1,3-丙二醇的分析方法。方法:试样经乙腈提取,提取液过滤后,上机测定。结果:采用GC-FID法和GC-MS法测定时,目标物质分别在0~50.00μg·mL^(-1)以及0~10.00μg·mL^(-1)线性范围内线性关系良好,相关系数r均大于0.9999;1,2-丙二醇的检出限分别为5 mg·kg^(-1)、1 mg·kg^(-1),1,3-丙二醇的检出限分别为8 mg·kg^(-1)、1 mg·kg^(-1);两种方法对应目标物质的平均加标回收率均≥89.2%,相对标准偏差均<5%。结论:GC-FID法与GC-MS法的灵敏度均较高、回收率高、重现性好,且操作简单快捷,适合于葛根粉中1,2-丙二醇和1,3-丙二醇的测定,可适应不同检测机构的需要。

Ru基负载型催化剂对2,2,4,4-四甲基-1,3-环丁二酮加氢效果的影响

以γ-Al_(2)O_(3)为载体、贵金属Ru为活性组分,制备了Ru基单金属催化剂Ru/Al_(2)O_(3),并以2,2,4,4-四甲基-1,3-环丁二酮(TMCB)为原料,在高压反应釜加氢反应评价装置上进行催化加氢合成2,2,4,4-四甲基-1,3-环丁二醇(CBDO)的工艺研究,并考察了相关工艺条件对加氢反应TMCB转化率和CBDO选择性的影响。实验结果表明,适宜反应条件为反应温度120℃、反应时间2 h、H_(2)压力4 MPa,在此条件下,TMCB的转化率为100%,CBDO的选择性为70.4%,顺反异构比为1.03。

Synthesis and Structural Characterization of a New Hydrogen-bonded Polyrotaxane of [Co(H_2O)_6]_(2+) with 1,1′-(Propane-1,3-diyl)dipyridinium-4-carboxylate

A new double betaine 1,1′-（propane-1,3-diyl）dipyridinium-4-carboxylate L has been synthesized. Reaction of 1, 1′-（propane-1,3-diyl）dipyridinium-4-carboxylate tetrahydrate 1 with Co（ClO4）2-6H2O leads to the formation of a new Co（Ⅱ） coordination compound, namely [Co（H2O）6]-2H2O-2L-2ClO4 2. The crystal structures of 1 and 2 have been determined by single-crystal X-ray diffraction method. Crystal data for 1. monoclinic, space group C2/c, a = 18.945（4）, b = 7.700（2）, c = l 1.888（2）A,β = 101.67（3）°, V = 1698.3（6） A^3, Z = 4, F（000） = 760.0, Dc = 1.402 g/cm^3, the final R = 0.0607 and wR = 0.1607 for 950 observed reflections （1 〉 2σ（I））; and those for 2： monoclinic, space group P21/c, a = 17.982（1）, b = 15.879 （1）, c = 7.0716（5）/A,β= 100.675（1）°, V= 1984.3（3） ,A^3 Z= 4, F（000） = 1010.0, Dc = 1.631 g/cm^3, the final R = 0.0316 and wR = 0.0896 for 3784 observed reflections （1 〉20（I））. Crystal structure analysis indicates that in 1, molecules of L in a ＂V-shaped＂ conformation are linked to chains sustained by O-H…O hydrogen bonds between carboxylate groups and solvent water molecules. The chains are joined by O-H…O and C-H…O hydrogen bonds to further expand into a three-dimensional structure. For 2, molecules of L in a ＂Z-shaped＂ conformation are linked by hydrogen bonds between carboxylate groups and aqua ligands to form a chain of loops running down the b axis. The （2D→2D） polythreading in compound 2 represents the mode of parallel interpenetration of 2D sheets, having polyrotaxane character.

D,L-1,2,2-三甲基环戊烷-1,3-二胺硝酸镍配合物的合成、结构及其和手性D-(+)-1,2,2-三甲基环戊烷-1,3-二胺氯化镍配合物的对比分析(英文)

complex[Ni(La) 2 ](NO 3 )2 (1)with bidentate racemic1,2,2-trimethylcyclopentane-1,3-diamine lig-and has been synthesized and characterized by IR,EA,ES-MS,and its X-ray diffracti on study reveals that the nickel (Ⅱ)abstract: center is tetra-coordinated by one D-and one L-diamine ligands,and a thre e-dimensional hydrogen-bond-sustained network is formed in the solid state by means of the eight-membered N-H...O hydrogen bond cy-cle.This compound also su pplies a good comparison to the chiral complex[Ni(L b )2 ]Cl 2 ·2H 2 O(2)(L b =D-(+)abstract:-1,2,2-trimethylcyclopentane-1,3-diamine)abstract:.CCDC:218122.

1,3-二氯丙烯药剂对土壤微生物数量和酶活性的影响

通过室内培养实验研究了1,3-二氯丙烯对土壤中微生物数量和土壤酶活性的影响,以评价其环境生态效应。结果表明,1,3-二氯丙烯熏蒸土壤后,各浓度处理对土壤真菌数量有强烈的抑制作用;对土壤细菌和放线菌的影响开始均表现为抑制作用,然后抑制作用减弱,逐渐表现出一定的激活作用。1,3-二氯丙烯熏蒸土壤后,高浓度处理对土壤脲酶表现为抑制-激活作用;低浓度处理表现为激活-抑制-激活作用。对蔗糖酶表现为激活-抑制作用,且抑制率逐渐增大。对过氧化氢酶表现为抑制-激活作用,50 d后施药土壤和对照组土壤的过氧化氢酶活性基本趋于一致。

富含1,3-丁二烯的裂解碳四选择加氢工艺研究

分别采用19mm的等温固定床反应器和50mm的绝热固定床反应器对富含1,3-丁二烯的裂解碳四进行了选择加氢工艺研究。通过等温固定床反应器选择加氢实验,确立了绝热固定床反应器选择加氢放大实验的操作条件:压力1.5M Pa、物料入口温度30℃、新鲜进料空速5h-1、氢与1,3-丁二烯的摩尔比1.2、循环比30。在此条件下,绝热固定床反应器选择加氢放大实验结果:1,3-丁二烯的质量分数由52.58%降至1.29%,1-丁烯的质量分数由11.06%提高到41.15%,单烯烃的选择性达到97.83%,1-丁烯的选择性达到58.67%。

间苯二酚催化加氢制备1,3-环己二醇的研究

通过间苯二酚的多相催化加氢制备得1,3-环己二醇,探讨了不同反应条件:溶剂、催化剂、反应温度和反应时间等对间苯二酚转化率及1,3-环己二醇收率的影响.反应结果表明:稳定镍的催化加氢作用明显强于超细还原铁粉和钯;催化加氢反应在非极性溶剂中几乎不反应,而在乙醇反应体系反应良好;由于1,3-环己二醇能进一步被转变为环己醇等副产物故反应时间不宜过长,反应温度,不宜过高.

间苯二酚转移加氢制备1,3-环己二酮

用转移加氢法由间苯二酚合成了1,3-环己二酮。适宜的反应条件为:以氢气还原的5%Pd/C 为催化剂,甲酸钠为氢供体,水作溶剂,在70℃反应1 h,1,3-环己二酮的收率为82.1%(HPLC)。考察了 PdCl_2/C的还原方式。催化剂经 XRD 表征确认了其活性组分是原子态的 Pd,初步确定催化剂失活的主要原因是杂质堵塞了活性炭载体中的微孔。

克雷伯杆菌利用生物柴油副产物甘油生产氢气和1,3-丙二醇的研究

以Klebsiella pneumoniae DSM2026为出发菌株，通过紫外线诱变，选育得到能耐较高浓度生物柴油副产物甘油生产H2和1，3-丙二醇（1，3-PD）的菌株21株，命名为Kp1～Kp21。通过比较，Kp8菌株产量最高，1，3-PD和H2产量分别达到0．36g/50mL和0．99mmol/50mL，比出发菌株分别提高了3．5倍和4．2倍。对Kp8菌株发酵条件进行优化，得到最佳培养条件为pH7．0，培养温度37℃，接种量10％（v/v），废甘油浓度为30g／L。在该条件下H2产量为1．0mmoL/50mL，1，3-PD产量为7．5g/L，甘油转化率为83．3％。