Effect of Hydrogen or Syngas Addition on Light Alkene Production by the Catalytic Oxidative Cracking of Hexane 氢气/合成气添加对正己烷催化氧化裂解制低碳烯烃反应的影响

 采用0.1%Pt/MgAl2O4催化剂研究了H2或合成气的添加对高碳烷烃模型化合物正己烷氧化裂解制低碳烯烃反应的影响. 添加H2实验中,随n(H2)/n(O2)从0增加到3,产物中COx的选择性迅速由22.4%降到4.3%,低碳烯烃的选择性则从61.5%增加到73.8%,正己烷的转化率从62.0%增加到72.8%. 添加合成气对低碳烯烃和CO选择性的影响与添加H2的影响相同,只是添加合成气时正己烷的转化率下降了6%左右. 添加合成气的正己烷氧化裂解过程可提供组成可调的产物(含有低碳烯烃、H2和CO),可不经分离直接用作加氢甲酰化生产低碳烯烃衍生物过程的原料.     

低温高活性熔铁催化剂上的超临界相费托合成反应

在固定床反应器中超临界相条件下研究了熔铁催化剂上的费托合成反应,发现在超临界介质中反应物和产物更容易扩散,较好地抑制了催化剂表面非活性碳的沉积,从而提高了费托合成反应中的CO转化率和烯烃选择性,增加了链增长因子,降低了甲烷选择性.同时,考察了超临界介质、反应温度、压力、H2/CO比和空速等条件对费托合成反应的影响.结果表明,C5-8正构烷烃在催化剂活性温度下都是适宜的超临界介质.当温度和压力都在介质的临界点以上时,介质表现出较好的传质与传热性能,可改善费托合成反应性能.     

在超临界正己烷介质中的F-T合成反应行为

在固定床反应器中,以正己烷为超临界介质,研究了三种Co催化剂（浸渍、喷雾干燥、双模催化剂）上的F-T合成反应行为。在相同的Co质量分数下,喷雾干燥催化剂和双模催化剂的活性接近,都高于浸渍催化剂。在喷雾干燥催化剂上CO的转化率显著高于浸渍催化剂。喷雾干燥催化剂F-T产物中具有高的低碳选择性和低的1-烯烃质量分数,然而在相近的CO转化率下,喷雾干燥和浸渍催化剂具有类似的1-烯烃质量分数。对于浸渍催化剂,当Co质量分数从5％增加到15％,CO转化率从8.3％增加到43.6％。含Co5％的催化剂比质量分数为10％、15％、20％催化剂的甲烷选择性低2.0%～3.0%,但产物中1-烯烃的质量分数明显要高。     

Co催化剂超临界相FT合成反应的研究

进行了Ｃｏ／ＳｉＯ２催化剂在超临界介质存在下的Ｆ－Ｔ合成反应，考察了反应介质（气相，超临界相）对ＣＯ转化率及烃收率的影响，重点研究了α－烯烃（１－Ｃ１４）加入以催化剂反应性能及产物分布的影响，结果表明，引入的超临界介质可以将反应热及重南产物从催化床层及对移去，改善了过程的传热及传质效率，使ＣＯ的转化率和烃收率显著提高，反尖体系中加入的α－烯烃，借助于超临界介质的作用可以吸附到催化剂表面，并发生链增     

异核金属簇〔PhCH_2Me_3N〕〔FeCo_3(CO)_(12)〕对烯烃氢甲酸化反应的催化作用

本文报导异核金属簇[RhCH_2 Me_3 N][FeCo_3(CO)_(12)]对烯烃氢甲酰化反应的催化作用.研究了反应温度、压力、溶剂等对反应的影响,考察了该金属簇对各类烯烃氢甲酰化反应的催化活性.该催化剂在较缓和的条件下具有较高的活性和选择性,4MPa,H_2:CO=1:1,120 ℃,反应1小时,1-己烯的转化率达80%以上,选择性大于90%.     

离子液体中锰卟啉催化双氧水氧化烯烃的研究

研究了离子液体中Mn(TFPP)Cl(meso-tatrakis(pentafluoropheyl)porphinato)manganese(Ⅲ)cloride锰卟啉催化烯烃的氧化反应.在离子液体-CH2C12混合溶剂中,以价廉、环境友好的H2O2为氧源,考察了离子液体结构、反应条件等对环氧化反应的影响.当氧化剂/环己烯/催化剂/咪唑=450∶150∶1∶75(摩尔比)时,室温下,在MMISM-CH2Cl2的混合溶剂中,环己烯的转化率和环氧环己烷的选择性可分别达到94.8%和95.5%,远高于在纯CH2Cl2中的实验结果.并在最优反应条件下考察了该催化剂体系对烯烃底物的适用性.此外,反应结束后,产物可以由正己烷萃取出来,考察了混合溶剂中Mn(TFPP)Cl催化剂的重复使用情况.     

Fe/MnO-ZnZSM-5双功能催化剂上合成气直接转化为芳烃的反应

 探讨了Fe／MnO－ZnZSM－5（n（SiO2）／n（Al2O3）＝50）双功能催化剂上合成气直接转化为芳烃的反应，考察了反应温度和Zn载量对CO转化率及芳烃选择性的影响．结果表明，Fe／MnO－ZnZSM－5具有良好的合成气芳构化性能，在V（CO）∶V（H2）∶V（Ar）＝3∶6∶1，SV＝1600h－1，p＝1．1MPa，T＝543K的条件下，CO转化率可达到98．1％，芳烃产物选择性可高达53．1％．催化剂经60h运转后，CO转化率仅降低0．5％，显示了良好的稳定性和应用前景．     

铁镍双金属催化剂用于二氧化碳加氢合成低碳烯烃的研究

研究了常压下铁镍双金属催化剂上进行二氧化碳催化加氢合成低碳烯烃的反应,考察了不同镍含量对二氧化碳转化率及产物选择性的影响,对反应前后催化剂物相的变化进行了ＸＲＤ、ＭＥＳ和ＸＰＳ研究。结果表明,少量镍的添加促进了催化剂中铁的还原,铁的碳化提高了二氧化碳转化率及烯烃选择性。添加１％ 镍时,反应温度３５０℃,反应空速５０００－ １ 条件下,产物中烯烃选择性达到５－３％ ,二氧化碳转化率为３２－６％ ,烯烷比为４－７。     

Fe－Mn催化剂对F－T合成反应的催化性能Ⅱ．中后期反应性能

 采用固定床积分反应器，详细考察了F－T合成反应用Fe－Mn催化剂运行900和1800h后的中后期反应性能．结果表明，该催化剂仍维持着较高的催化活性及稳定性；与初期反应性能相比，运行900h后CH4选择性有明显升高的趋势，运行1800h后CH4选择性进一步升高．运行2200h后，通过降低原料气的H2／CO比和提高反应压力，可明显改善烃产物的选择性．在n（H2）／n（CO）＝0．62，GHSV＝2300h－1，p＝3．02MPa和θ＝283℃的条件下，CO转化率可达75．6％，总有效烃（C＝2～4＋C＋5）的选择性可达89．0％，CH4选择性为5．7％．这表明该催化剂具有良好的可操作性，且特别适合于由煤制合成气制液体燃料和C2～4低碳烯烃，在浆态床反应器中有潜在的应用前景．     

还原气氛对CoFe/SBA-15催化剂F-T反应性能的影响

考察了不同还原气氛处理CoFe/SBA-15催化剂对F-T反应性能的影响。结果表明,H2气氛下有利于六方钴的生成;催化剂的活性取决于钴含量,随着钴含量的增加,F-T反应中CO转化率增加,C5+选择性增加。随着铁含量的增加,催化剂表现了较高的CO2选择性。CO还原有利于立方钴的生成,导致催化活性相比H2还原的催化剂活性要低。同时CO还原容易产生积炭使催化剂的钴活性位被覆盖,导致甲烷选择性随着钴含量增加而升高。但碳化铁的生成有利于提高20Fe/SBA-15催化剂的活性,有利于低碳烃生成及C2~4烃烯烷比增加。     

Enthalpy of solution of 1,4-naphthoquinone in CO2 + n-pentane in the critical region of the binary mixture: mechanism of solubility enhancement

The enthalpy of solution (Delta(solv)H(m)) and solubility of 1,4-naphthoquinone in CO(2) + n-pentane were measured at 308.15 K in the critical region of the binary fluid. In order to study the effect of phase behavior of the mixed solvent on Delta(solv)H(m), the experiments were carried out in the supercritical (SC) and subcritical region of the binary solvent. The density of the mixed solvent in different conditions was determined. The isothermal compressibility (K(T)) of the mixed solvent, and the partial molar volume (V(n-pentane)) of n-pentane in the solution were calculated. It was demonstrated that the Delta(solv)H(m) was negative in all conditions. Delta(solv)H(m) is nearly independent of pressure or density in all the solvents in a high-density region, in which compressibility of the solvent is very small; this indicates that the intermolecular interaction between the solvent and the solute is similar to that for liquid solutions. It is very interesting that Delta(solv)H(m) in the mixed SC fluid differs from the Delta(solv)H(m) in mixed subcritical fluids. The absolute value of Delta(solv)H(m) in the mixed SC fluid is close to that in pure SC CO(2) in the high-density region, and is much lower than that in pure SC CO(2) in the low-density region. In the mixed subcritical fluids, the Delta(solv)H(m) is also close to that in the pure CO(2) in the high-density region. However, at the same density, the absolute value of Delta(solv)H(m) in the binary subcritical fluid is larger than that in pure CO(2) in the high-compressible region of the mixed solvent. The main reason for this is that the degree of clustering in the SC solutions is small at the density in which the degree of clustering is large in the subcritical solutions. It can be concluded that solubility enhancement by n-pentane in the mixed SC fluid is entropy driven. In contrast, the solubility enhancement by n-pentane in subcritical fluids is enthalpy driven. The intermolecular interaction in the SC solutions and subcritical solutions can be significantly different even if their densities are the same.     

Effect of pressure on the selectivity for the esterification of ethylene glycol with propionic acid in supercritical CO2

The esterification of ethylene glycol with propionic acid was investigated in supercritical CO2 at 50.0 degrees C. The effect of pressure on equilibrium conversion and selectivity of ethylene glycol monopropionate (monoester) and ethylene glycol dipropinonate (diester) was studied systematically. It was shown that the equilibrium conversion and selectivity was nearly independent of pressure as pressure was lower than 9 MPa. At higher pressure, however, the yield and selectivity of the diester increased considerably, while those of the monoester decreased with increasing pressure. The main reason was that reactants and products distributed between the vapor phase and liquid phase at higher pressures. The solvent power of CO2 for the diester is stronger than that for the monoester. More diester molecules in the liquid phase were extracted into the vapor at higher pressures, which shifted equilibrium of the consecutive reversible reactions.     

Ni/Al2O3催化剂表面状态对CH4氧化反应的影响

采用瞬变响应技术研究了常压700℃条件下气相O2、Ni/Al2O3催化剂表面上可逆吸附氧物种及催化剂的表面状态对CH4吸附、反应以及CH4部分氧化反应的影响,同时也对CH4部分氧化制合成气反应过程中催化剂表面所处的状态进行了研究.结果表明,如果催化剂表面处于氧化态,CH4不能吸附分解,只能通过RidealEley机理与催化剂表面的吸附氧进行非选择性氧化反应,这将严重影响CH4的转化和目的产物H2、CO的选择性.只有在还原的催化剂上,CH4部分氧化制合成气反应才能高转化、高选择性地进行.在CH4部分氧化制合成气反应过程中,催化剂表面处于还原态,不存在多余的中间氧物种NiO,但存在少量的碳物种,这有利于保持催化剂的还原态和抑制CO2的生成.     

Supercritical extraction of lycopene from tomato industrial wastes with ethane

Supercritical fluid extraction of all-E-lycopene from tomato industrial wastes (mixture of skins and seeds) was carried out in a semi-continuous flow apparatus using ethane as supercritical solvent. The effect of pressure, temperature, feed particle size, solvent superficial velocity and matrix initial composition was evaluated. Moreover, the yield of the extraction was compared with that obtained with other supercritical solvents (supercritical CO? and a near critical mixture of ethane and propane). The recovery of all-E-lycopene increased with pressure, decreased with the increase of the particle size in the initial stages of the extraction and was not practically affected by the solvent superficial velocity. The effect of the temperature was more complex. When the temperature increased from 40 to 60 °C the recovery of all-E-lycopene increased from 80 to 90%. However, for a further increase to 80 °C, the recovery remained almost the same, indicating that some E-Z isomerization could have occurred, as well as some degradation of lycopene. The recovery of all-E-lycopene was almost the same for feed samples with different all-E-lycopene content. Furthermore, when a batch with a higher all-E-lycopene content was used, supercritical ethane and a near critical mixture of ethane and propane showed to be better solvents than supercritical CO? leading to a faster extraction with a higher recovery of the carotenoid.     

Effect of alcohol solvents treated ZrO（OH）2 hydrogel on properties of ZrO2 and its catalytic performance in isosynthesis

A series of ZrO2 catalysts were prepared by treating ZrO(OH)2 hydrogel with different alcohol solvents (C2-C4 alcohols) and calcining under N2 flow at 773 K for 3 h. The obtained ZrO2 catalysts were systematically characterized by the methods of N2 adsorption-desorption, powder X-ray diffraction, NH3 temperature-programmed desorption, and CO2 temperature-programmed desorption. The catalytic performance of each catalyst was evaluated in the selective synthesis of iso-C4 (isobutene and isobutane) and light olefins (C2= ～C4= ) from CO hydrogenation. The specific surface area increased for the ZrO2 catalysts obtained by treating ZrO(OH)2 hydrogel with different alcohol solvents. The amounts of both acidic and basic sites on the catalyst surface increased obviously. The catalytic activity (CO conversion) of ZrO2 catalysts also increased after the treatment with different alcohol solvents. The highest activity was obtained over the catalyst which was pretreated with isopropanol. However, alcohol solvent treatment retarded the transformation of ZrO2 crystal structure from tetragonal phase to monoclinic phase, and subsequently resulted in the decrease of monoclinic phase in ZrO2, which led to the decrease of olefin selectivity in corresponding hydrocarbon products (C2=～C4= /CH).     

Fischer-Tropsch Reaction Kinetics of Cobalt Catalyst in Supercritical Phase

Fischer-Tropsch synthesis under supercritical phase condition was examined in a continuous and a high-pressure fixed bed reactor by employing a cobalt catalyst (Co-R.Ru/γ-Al2O3). An integral reactor model involving Fischer-Tropsch reaction kinetics in the supercritical fluid n-hexane was used to describe the overall performance. On the basis of Langmuir-Hinshelwood-Hougen-Watson (LHHW) model, the reaction rate constants were obtained for the rate equations of CO conversion to CH4 formation under supercritical conditions.     

甲烷在SrO-La2O3/CaO催化剂上的氧化偶联Ⅱ.反应动力学的研究

在２０％Ｌａ２Ｏ３／ＣａＯ（ＬＣ）催化剂中添加ＳｒＯ（添加ＳｒＯ的ＬＣ以ＳＬＣ表示）明显地提高了反应活性和Ｃ２选择性。反应动力学研究表明，ＬＣ和ＳＬＣ催化剂在甲烷氧化偶联反应中，在表观活化能和表观反应级数上存在很大的差异。ＬＣ催化剂在ＣＨ４转化以及Ｃ２和ＣＯｘ形成过程中，表观活化能大于ＳＬＣ催化剂，而ＳＬＣ催化剂的指前因子小于ＬＣ体系，两者存在着补偿形象。ＳＬＣ催化剂的反应速率常数比ｋｃ２／ｋＣＨ     

Some Organic Reactions in Supercritical Carbon Dioxide

Organic reactions in supercritical carbon dioxide (scCO2) have facilitated great progress in recent years . ScCO2, as an environmentally friendly reaction medium, may be a substitute for 1 volatile and toxic organic solvents and show some special advantages. Firstly, CO2 is inexpensive, nonflammable, nontoxic and chemical inert under many conditions. Secondly, scCO2 possesses hybrid properties of both liquid and gas, to the advantage of some reactions involving gaseous reagents. Control o…