Ni基催化剂上的乙烷部分氧化制合成气

There is abundant supply of light alkanes and relatively few routes of converting them to more valuable products. Although CH4 predominates in natural gas, it also contains C2H6, C3H8 and C4H10 (from 5 % to 30% ), and with C2H6 as the most abundant secondary component[1]. Partial oxidation of methane to syngas (CH4 +0.5O2 →CO + 2H2) over nickel-based catalysts has received intensive attention[2]and much research has been devoted to conversion of ethane to ethylene[3]. Ethylene has been shown to be formed from ethane by thermal dehydrogenation (C2H6 →C2H4 + H2) and oxidative dehydrogenation (C2H6 + 0. 5O2 →C2H4 + H2O). These processes are operated under severely fuel-rich conditions. The carbon-deposition and consequent deactivation of the catalysts are major problems, which leads to poor conversion of the above mentioned reactions. As an alternative strategy for the elaboration of ethane, little work on the partial oxidation of ethane (POE) to syngas over nickel-based catalysts has been reported. Provided it could be produced from C2H6with high selectivity and high conversion over nickel-based catalysts, syngas could be directly obtained from natural gas including CH4 and C2H6 with high selectivity and conversion. This may lead to better utilization of the light fractions from natural gas and refineries. In the present paper, POE to syngas over nickel-based catalysts was investigated.     

Effects of Temperature and Catalyst to Oil Weight Ratio on the Catalytic Conversion of Heavy Oil to Propylene Using ZSM-5 and USY Catalysts

It is useful for practical operation to study the rules of production of propylene by the catalytic conversion of heavy oil in FCC (fluid catalytic cracking). The effects of temperature and C/O ratio (catalyst to oil weight ratio) on the distribution of the product and the yield of propylene were investigated on a micro reactor unit with two model catalysts, namely ZSM-5/Al2O3 and USY/Al2O3, and Fushun vacuum gas oil (VGO) was used as the feedstock. The conversion of heavy oil over ZSM-5 catalyst can be comparable to that of USY catalyst at high temperature and high C/O ratio. The rate of conversion of heavy oil using the ZSM-5 equilibrium catalyst is lower compared with the USY equilibrium catalyst under the general FCC conditions and this can be attributed to the poor steam ability of the ZSM-5 equilibrium catalyst. The difference in pore topologies of USY and ZSM-5 is the reason why the principal products for the above two catalysts is different, namely gasoline and liquid petroleum gas (LPG), repspectively. So the LPG selectivity, especially the propylene selectivity, may decline if USY is added into the FCC catalyst for maximizing the production of propylene. Increasing the C/O ratio is the most economical method for the increase of LPG yield than the increase of the temperature of the two model catalysts, because the loss of light oil is less in the former case. There is an inverse correlation between HTC (hydrogen transfer coefficient) and the yield of propylene, and restricting the hydrogen transfer reaction is the more important measure in increasing the yield of propylene of the ZSM-5 catalyst. The ethylene yield of ZSM-5/Al2O3 is higher, but the gaseous side products with low value are not enhanced when ZSM-5 catalyst is used. Moreover, for LPG and the end products, dry gas and coke, their ranges of reaction conditions to which their yields are dependent are different, and that of end products is more severe than that of LPG. So it is clear that maximizing LPG and propylene and restricting dry gas and coke can be both achieved via increasing the severity of reaction conditions among the range of reaction conditions which LPG yield is sensitive to.     

碱金属和氯离子对Mn_2O_3－Na_2WO_4／SiO_2催化剂甲烷氧化偶联反

本文考察了碱金属和氯离子对Ｍｎ２Ｏ３－Ｎａ２ＷＯ４／ＳｉＯ２催化剂甲烷氧化偶联反应性能的影响，结果表明，只有在氯离子和碱金属的共同作用下才能有效地提高Ｃ２烃的收率及其选择性．催化剂经ＮａＣｌ改性后，Ｃ２烃收率为２２％，并可获较高的烯烷比．在考察范围内增加接触时间（Ｗ／Ｆ），催化剂选择性保持不变，但乙烯的选择性呈上升趋势．钠盐Ｎａ２ＷＯ４、Ｎａ４Ｐ２Ｏ７、Ｎａ２ＳＯ４、Ｎａ２ＣＯ３及Ｎａ２Ｂ４Ｏ７对稳定催化剂的贡献按上述顺序逐渐减小．对ＮａＣｌ－Ｍｎ２Ｏ３－Ｎａ２ＷＯ４／ＳｉＯ２催化剂进行了稳定性考察，使用ＸＰＳ、ＸＲＤ和红外光谱对经历不同反应时间的催化剂进行了表征．     

Synthesis of Na2WO4-MnxOy supported on SiO2 or La2O3 as fiber catalysts by electrospinning for oxidative coupling of methane

The oxidative coupling of methane (OCM) is an attractive route to convert natural gas directly into value-added chemical products (C₂₊). This work comparatively investigated SiO₂- or La₂O₃-supported Na₂WO₄-Mn_xO_y (denoted as NWM) catalysts in powder and fiber forms. The powder catalysts were prepared using a co-impregnation method and the fiber catalysts were prepared successfully using an electrospinning technique. The NWM/La₂O₃ fiber catalysts were activated at low temperature (500 °C) and had a 4.7% C₂₊ yield, with the maximum C₂₊ yield of 9.6% at 650 °C, while the NWM/SiO₂ fiber catalyst was activated at 650 °C and had a maximum C₂₊ yield of 20.4% at 700 °C. The XPS results in the O 1s region indicated that NWM/La₂O₃ had a lower binding energy than NWM/SiO₂, suggesting that the lattice oxygen species is easily released from the catalyst surface and creates vacancy sites that enhance performance. The stability test of the catalysts indicated that the La₂O₃-containing catalysts had excellent activity and high thermal stability, while the SiO₂-containing catalysts had a higher C₂₊ yield when the prepared catalysts were compared at 700 °C. Considering the same component catalysts, the fiber catalysts achieved higher performance because their heat and mass transfer properties were enhanced.     

Production of propylene from an unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts

An unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts has been studied as an alternative route for the production of propylene. Complete conversion of 2-pentene and propylene yield as high as 88 wt% were obtained under mild reaction conditions at 35°C and atmospheric pressure. Unlike the conventional metathesis of ethylene and 2-butenes in which isomerization is a competing side reaction, the isomerization of 1-butene product from the unconventional metathesis of ethylene and 2-pentene to 2-butenes can further react with excess ethylene in the feed, resulting in additional increase in propylene yield. The secondary metathesis reaction was found to be favored under ethylene/2-pentene (E/2P) molar ratio 3 and gas hourly space velocity (GHSV) 1000 h-1 at the reaction temperature of 35°C. No catalyst deactivation was observed during the 455 min time-on-stream under the selected reaction conditions.     

Gas Phase Polymerisation of Ethylene with Supported Titanium-Nickel Catalysts

Olefins gas phase polymerization uses generally supported titanium catalyst systems inindustrial production. The polymerization of olefins with late transition metal catalysthas recently attracted considerable interestl-2. The new catalyst family shares many ofthe advantages of metallocene catalysts in terms of activity and control of polymerproperties and, in addition, the new catalysts yield homopolymer of ethylene with veryhigh branching degrees and branching degree can be controlled.A new …     

Catalyst/cocatalyst nuclearity effects in single-site polymerization. Enhanced polyethylene branching and alpha-olefin comonomer enchainment in polymerizations mediated by binuclear catalysts and cocatalysts via a new enchainment pathway

The binuclear "constrained geometry catalyst" (CGC) (mu-CH2CH2-3,3'){(eta5-indenyl )[1-Me2Si(tBuN)](ZrMe2)}2 [EBICGC(ZrMe2)2; Zr2] and the trityl bisborate dianion (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2- (B2) have been synthesized to serve as new types of multicenter homogeneous olefin polymerization catalysts and cocatalysts, respectively. Additionally, the complex [1-Me2Si(3-ethylindenyl)(tBuN)]ZrMe2 (Zr1) was synthesized as a mononuclear control. For the bimetallic catalyst or bisborate cocatalyst, high effective local active site concentrations and catalyst center-catalyst center cooperative effects are evidenced by bringing the catalytic centers together via either covalent or electrostatic bonding. For ethylene homopolymerization at constant conversion, the branch content of the polyolefin products (primarily ethyl branches) is dramatically increased as catalyst or cocatalyst nuclearity is increased. Moreover, catalyst and cocatalyst nuclearity effects are approximately additive. Compared to the catalyst derived from monometallic Zr1 and monofunctional Ph3C+B(C6F5)4- (B1), the active catalyst derived from bimetallic Zr2 and bifunctional B2 produces approximately 11 times more ethyl branches in ethylene homopolymerization via a process which is predominantly intradimer in character. Moreover, approximately 3 times more 1-hexene incorporation in ethylene + 1-hexene copolymerization and approximately 4 times more 1-pentene incorporation in ethylene + 1-pentene copolymerization are observed for Zr2 + B2 versus Zr1 + B1.     

Effect of La2O3／γ—Al2O3 Catalyst on the Activation of CH4 and CO2 to C2 Hydrocarbons under Non—equilibrium Plasma

In the reaction of methane and carbon dioxide to C2 hydrocabons under non-equilibrium plasma, methane conversion was decreased,but selectivity of C2 hydroxarbons was increased when using La2O3/γ-Al2O3 as catalyst. So the yield of C2 hydrocarbons was higher than using plasma alone. The synergism of La2O3/γ-Al2O3 and plasma gave methane conversion of 24.9% and C2 yield of 18.1%. The distribution of C2 hydrocarbons changed when Pd-La2O3/γ-Al2O3 was used as catalyst,the major C2 product was ethylene.     

Effect of La_2O_3/γAl_2O_3 Catalyst on the Activation of CH_4 and CO_2 to C_02 Hydrocarbons under Non-equilibrium Plasma

The oxidative coupling of methane (OCM) to C2 hydrocarbons using carbon dioxide as oxidant is an attractive process from environmental point of view. Only a few research papers reported for it1-3. In general, the yield of C2 hydrocarbons was about 6%. This indicated that the method of catalytic activation was unfavorable to the reaction. It is necessary for us to find a new method in order to activate reaction and improve C2 hydrocarbon yield. Non-equilibrium plasma is a cold plasma in…     

Pyrolysis of Glucose over Two Amphoteric Metal Oxides

The catalytic pyrolysis of glucose over amphoteric metal oxide, ZnO or γ-Al2O3, was studied comparatively with direct pyrolysis. The effects of catalyst to glucose ratio on the yields of pyrolytic products and on the chemical composition of the liquid products were discussed. Compared with the pyrolytic products of direct pyrolysis, the amount of residual char decreased, whereas the gas yield increased in the presence of the catalysts. The highest liquid yield over ZnO(49.5%) was obtained when the ratio of ...     

Mo-Zn/HZSM-5催化剂上甲烷与丙烷混合物的无氧芳构化

研究了甲烷和丙烷的混合气体在x%Mo+6%Zn/HZSM-5催化剂上(x=0.3,0.5,0.7,0.9)的无氧芳构化反应性能.结果表明,在873K,GHSV=3L/(g·h)和n(C₁)/n(C₃)=1.0条件下,甲烷的转化率在29%～35%之间,芳烃选择性大于80%.其中0.7%Mo+6%Zn/HZSM-5对甲烷表现出最优的活性,甲烷转化率达到34.8%,丙烷转化率为69.6%.探讨了反应时间和n(C₁)/n(C₃)比对甲烷和丙烷转化率及其产物分布的影响.结果显示,丙烷的存在促使甲烷活化并参与芳构化反应.同位素13^CH₄示踪实验发现,13^C进入了C₆H₆⁺,C₇H₈⁺和C₈H₁₀⁺碎片中,进一步证实了甲烷进入芳烃形成过程.此种用丙烷活化甲烷的过程可能为天然气和炼厂气的直接利用提供了一个新的反应途径.     

Gas Phase Polymerization of Ethylene with Supported Titanium-Nickel Catalysts

A new ditransition-metal catalyst system TiCl4-NiCl2/MgCl2-SiO2/AlR3 was prepared.Gas phase polymerization of ethylene with the catalysts has been studied.The kinetic curves of gas phase polymerization showed a decline.The catalystic efficiency and polymerization reaction rates have a optimum value when Ni content of the catalysts was 12.5%(mol).The products obtained are branched polyethylene.     

Stabilization of Cu/ZnO Based Catalysts by Nickel Additive in Methanol Decomposition

A series of Cu/Zn based catalysts with and without Ni, prepared by the co-precipitation method, has been studied for methanol decomposition. CO and H2 are the major products. The Cu/Zn catalysts show a low initial activity and a poor stability. The formation of the CuZn alloys was observed in the deactivated Cu/Zn catalysts which were used for methanol decomposition at 250 . When small amounts of Ni were added in the catalyst, the Cu/Zn/Ni(molar ratio 5/4/ x) catalysts showed a high activity at a low temperature. The activity and the stability of the catalyst depend on the nickel content. The activity of the Cu/Zn/Ni catalysts was maintained at a. relatively stable value of 78% conversion of methanol with 95% selectivity of H2, 93% selectivity of CO, and a more than 70% yield of hydrogen was obtained at 250 C when x >1. The stability of the Cu/Zn/Ni (molar ratio 5/4/x) catalysts showed the maximum (ca 88%) when x=1. The stabilization effect of nickel on the Cu/Zn based catalysts may lead to the increasin     

纳米Cr2O3系列催化剂上CO2氧化乙烷脱氢制乙烯反应

 采用溶胶－凝胶法和共沸蒸馏法耦合技术制备了纳米Cr2O3催化剂，并采用共沉淀法和共沸蒸馏法耦合技术制备了纳米Cr2O3／Al2O3，Cr2O3／ZrO2和Cr2O3／MgO复合催化剂．应用BET，XRD，XPS，TPR和TEM等物理化学方法对催化剂的结构和物化性质进行了表征，并考察了该系列催化剂上CO2氧化乙烷脱氢制乙烯的反应性能．结果表明，纳米Cr2O3催化剂上乙烷和CO2的转化率均明显高于常规Cr2O3催化剂，但乙烯的选择性低于常规Cr2O3催化剂；纳米复合催化剂中的复合成分显著影响催化剂的催化性能．其中，10％Cr2O3／MgO纳米复合催化剂在温度为973K时，乙烷转化率和乙烯选择性分别可达到61．54％和94．79％．纳米催化剂表面Cr的还原性以及Cr6＋／Cr3＋比值是影响乙烷转化率和乙烯选择性的重要因素．     

Experimental investigation of fluidized-bed reactor performance for oxidative coupling of methane

Performance of the oxidative coupling of methane in fluidized-bed reactor was experimentally investigated using Mn-Na2WO4/SiO2,La2O3/CaO and La2O3-SrO/CaO catalysts.These catalysts were found to be stable,especially Mn-Na2WO4/SiO2 catalyst.The effect of sodium content of this catalyst was analyzed and the challenge of catalyst agglomeration was addressed using proper catalyst composition of 2%Mn2.2%Na2WO4/SiO2.For other two catalysts,the effect of Lanthanum-Strontium content was analyzed and 10%La2O 3-20%SrO/CaO catalyst was found to provide higher ethylene yield than La2O3/CaO catalyst.Furthermore,the effect of operating parameters such as temperature and methane to oxygen ratio were also reviewed.The highest ethylene and ethane (C2) yield was achieved with the lowest methane to oxygen ratio around 2.40.5% selectivity to ethylene and ethane and 41% methane conversion were achieved over La2O3-SrO/CaO catalyst while over Mn-Na2WO4 /SiO2 catalyst,40% and 48% were recorded,respectively.Moreover,the consecutive effects of nitrogen dilution,ethylene to ethane production ratio and other performance indicators on the down-stream process units were qualitatively discussed and Mn-Na2WO4/SiO2 catalyst showed a better performance in the reactor and process scale analysis.     

Comparison between the “one-step” and “two-step” catalytic pyrolysis of pine bark

In this study, one-step and two-step pyrolysis systems were compared in the pyrolysis of pine bark. One-step pyrolysis was performed in a fixed bed reactor with and without catalyst. Two-step pyrolysis was carried out in a dual reactor system over catalyst; the first reactor containing no catalyst whereas the second reactor containing catalyst to upgrade the thermally cracked products. The catalysts used in the pyrolysis systems were ReUS-Y, red mud and ZSM-5. In thermal pyrolysis, the pyrolysis system mainly affected the relative amount of bio-oil. The bio-oil yields obtained from two-step thermal pyrolysis were higher than the yields from one-step thermal pyrolysis. In the catalytic runs, ReUS-Y catalyst slightly decreased the char formation with a consequent increase in aqueous phase yield in the case of one-step pyrolysis. However, the catalysts decreased the bio-oil yield with a consequent increase in the gas yield in the case of two-step pyrolysis. The general compositions of bio-oils obtained from both two pyrolysis systems were affected by using catalysts. In the case of one-step pyrolysis, the formation of water and water soluble compounds were reduced by using ReUS-Y catalyst. In the case of two-step pyrolysis, both ZSM-5 and red mud increased the formation of water soluble compounds while they decreased water formation. In contrast, ReUS-Y decreased the formation of water soluble compounds and increased the amount of pyrolytic lignin compounds in bio-oil. Fuel characteristics of pyrolysis products (gas, bio-oil and char) for both two pyrolysis systems were also investigated comparatively.     

Ethylene production by the oxidative condensation of methane in the presence of MnMW/SiO<Subscript>2</Subscript> catalysts (M = Na,K, and Rb)

The samples of MnMW/SiO₂ (M = Na, K, and Rb) were synthesized using various synthesis methods under varied heat treatment conditions and their physicochemical properties and activity in the reaction of the oxidative condensation of methane (OCM) were studied for the development of an effective catalyst for the resource-saving process of natural gas conversion into ethylene. It was found that the preparation method exerts an effect on the textural characteristics of the samples and the reducing properties of the cations of manganese and tungsten. It was determined that the composition of a W-containing phase depends on the alkali metal, and a ratio between the polymorphous modifications of SiO₂ is controlled by the method of synthesis and the conditions of catalyst heat treatment. It was established that the yield of C₂ hydrocarbons in the OCM reaction increased with the use of incipient wetness impregnation instead of the method of mixing with a suspension for catalyst preparation and with an increase in the catalyst heat treatment temperature from 700 to 1000°C. The optimum composition of the catalyst and the condition of its synthesis were found: 2Mn_0.8Na₃W/SiO₂ obtained by the impregnation method and calcined at 1000°C ensured the yield of target products of ~20% with a CH₄ conversion of ~35% at a reaction temperature of 850°C.     

中孔分子筛负载钴催化剂制备及其在费-托合成中的催化性能

 以HMS,MCM－41,AlHMS和ZrO2／HMS等中孔分子筛为载体,采用孔体积浸渍法制备了系列负载型钴催化剂．XRD测定结果表明,Co氧化物完全分散于分子筛内表面,载体仍保持中孔分子筛的特征;低温N2吸附测定结果表明,表面负载金属钴后,分子筛的比表面积和孔体积下降,孔径减小,孔壁增厚．比较了不同中孔分子筛负载Co催化剂在F－T反应中的催化性能,以短程六角对称的HMS为载体,有利于F－T反应中的链增长,烃类产物主要为微晶蜡;以ZrO2／HMS为载体可抑制CH4的生成,提高C5＋的选择性．     

Cloride-derived copper electrode for efficient electrochemical reduction of CO2 to ethylene

Transformation of CuCl into cubic structure of bi-phasic Cu₂O-Cu (CB-Cu) enhanced production of ethylene from electrochemical reduction of CO₂.     

廉价铁基催化剂Ｆ-Ｔ合成反应性能初探

以四个廉价的FeSO4工业原料为铁源,采用连续共沉淀法制得含铁浆料,再用喷雾干燥法制得微米级球状Fe-Cu-Ｋ-SiO2催化剂。在Ｈ2/ＣＯ=2、526Ｋ、2 0MPa、2000ｈ-1条件下于固定床反应器上考察了这四个铁基催化剂的Ｆ-Ｔ合成反应活性、选择性和稳定性,结果表明在240ｈ运行时间内,该四个催化剂均表现出良好的反应活性和选择性,而稳定性则有不同程度的下降,其中2#催化剂性能相对较优,初始ＣＯ转化率为77.89%,经历反应诱导期40ｈ时达到89 58%,其后ＣＯ转化率逐渐下降,失活速率为1 33%/ｄ;在整个运行期间ＣＨ4选择性维持在4%左右,Ｃ+5选择性在80%左右。