Na促进的CuCoMn催化剂催化生物质合成气合成高醇

研究钠促进的CuCoMn催化剂的特性及其在生物质气化合成气合成高醇中的应用. 研究了催化剂中Na含量及合成条件(温度、压力和空速)对生物质基合成气合成高醇性能的影响. 发现CuCoMnNa_0.1催化剂较适合高醇合成, 在300 °C以下, 随着温度的上升, 碳转化率增大, 而醇选择性降低. 压力的增加有利于醇的合成, 增大空速会明显降低碳转化率, 但醇时空产率则因转换频率的增加而增大. 在所考察的范围内, 醇产率最高达到304.6 g·kg^-1·h^-1, 其中C₂₊高醇(C₂-C₆醇)占64.4% (w, 质量分数). 醇产物和烃产物均符合ASF (Anderson- Schulz-Flory)分布关系. 根据催化剂性能与表征分析, Na的加入有利于提高生物质气化合成气合成高醇的选择性和活性元素Cu、Co的分散性. X射线光电子谱(XPS)测试结果显示反应后的催化剂表面上, Cu以Cu⁺和Cu⁰的混合形式存在, 而Co则是Co²⁺/Co³⁺和Co⁰的混合物. 增加Na的含量, Cu⁰/Cu⁺比率和Co⁰的强度均随之减小.     

Effects of Activation Atmospheres on Structure and Activity of Mo-based Catalyst for Synthesis of Higher Alcohols

Activated carbon supported Mo-based catalysts were prepared and reduced under different activation atmospheres, including pure H₂, syngas (H₂/CO=2/1), and pure CO. The catalysts structures were characterized by X-ray diffraction, X-ray absorption fine structure, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The catalytic performance for the higher alcohol synthesis from syngas was tested. The pure H₂ treatment showed a high reduction capacity. The presence of a large amount of metallic Co⁰. and low valence state Mo^φ+ (0<φ<2) on the surface suggested a super activity for the CO dissociation and hydrogenation, which promoted hydrocarbons formation and reduced the alcohol selectivity. In contrast, the pure CO-reduced catalyst had a low reduction degree. The Mo and Co species at the catalyst mainly existed in the form of Mo⁴⁺ and Co²⁺. The syngas-reduced catalyst showed the highest activity and selectivity for the higher alcohols synthesis. We suggest that the syngas treatment had an appropriate reduction capacity that is between those of pure H₂ and pure CO and led to the coexistence of multivalent Co species as well as the enrichment of Mo^δ+ on the catalyst's surface. The synergistic effects between these active species provided a better cooperativity and equilibrium between the CO dissociation, hydrogenation and CO insertion and thus contributed beneficially to the formation of higher alcohols.     

Carboxylate Platform: The MixAlco Process Part 2: Process Economics

The MixAlco process employs a mixed culture of acid-forming microorganisms to convert biomass to carboxylate salts, which are concentrated via vapor-compression evaporation and subsequently chemically converted to other chemical and fuel products. To make alcohols, hydrogen is required, which can be supplied from a number of processes, including gasifying biomass, separation from fermentor gases, methane reforming, or electrolysis. Using zeolite catalysts, the alcohols can be oligomerized into hydrocarbons, such as gasoline. A 40-tonne/h plant processing municipal solid waste ($45/tonne tipping fee) and using hydrogen from a pipeline or refinery ($2.00/kg H₂) can sell alcohols for $1.13/gal or gasoline for $1.75/gal with a 15% return on investment ($0.61/gal of alcohol or $0.99/gal of gasoline for cash costs only). The capital cost is $1.95/annual gallon of mixed alcohols. An 800-tonne/h plant processing high-yield biomass ($60/tonne) and gasifying fermentation residues and waste biomass to hydrogen ($1.42/kg H₂) can sell alcohols for $1.33/gal or gasoline for $2.04/gal with a 15% return on investment ($1.08/gal of alcohol or $1.68/gal of gasoline for cash costs only). The capital cost for the alcohol and gasification plants at 800 tonnes/h is $1.45/annual gallon of mixed alcohols.     

Synthesis of Higher Alcohols from Syngas over Alkali Promoted K-Co-Mo Catalysts Supported on Multi-walled Carbon Nanotubes

A series of carbon nanotubes-supported K-Co-Mo catalysts were prepared by a sol-gel method combined with incipient wetness impregnation.The catalyst structures were characterized by X-ray diffraction,N₂ adsorption-desorption,transmission electron microscopy and H₂-TPD,and its catalytic performance toward the synthesis of higher alcohols from syngas was investigated.The as-prepared catalyst particles had a low crystallization degree and high dispersion on the outer and inner surface of CNTs.The uniform mesoporous structure of CNTs increased the diffusion rate of reactants and products,thus promoting the reaction conversion.Furthermore,the incorporation of CNTs support led to a high capability of hydrogen absorption and spillover and promoted the formation of alkyl group,which served as the key intermediate for the alcohol formation and carbon chain growth.Benefiting from these characteristics,the CNTs supported Mo-based catalyst showed the excellent catalytic performance for the higher alcohols synthesis as compared to the unsupported catalyst and activated carbon supported catalyst.     

Higher-alcohols biorefinery

The concept of a biorefinery for higher-alcohol production is to integrate ethanol and methanol formation via fermentation and biomass gasification, respectively, with, conversion of these simple alcohol intermediates into higher alcohols via the Guerbet reaction. 1-Butanol results from the selfcondensation of ethanol in this multistep reaction occurring on a single catalytic bed. Combining methanol with ethanol gives a mixture of propanol, isobutanol, and 2-methyl-1-butanol. All of these higher alcohols are usefulas solvents, chemical intermediates, and fuel additives and, consequently, have higher market values than the simple alcohol intermediates. Several new catalysts for the condensation of ethanol and alcohol mixtures to higher alcohols were designed and tested under a variety of conditions. Reactions of methanol ethanol mixtures gave as high as 100% conversion of the ethanol to form high yields of isobutanol with smaller amounts of 1-propanol, the amounts in the mixture depending on the starting mixture. The most successful catalysts are multifunctional with basic and hydrogen transfer components.     

Pressure swing adsorption for CO<Subscript>2</Subscript> capture in Fischer-Tropsch fuels production from biomass

Environmental concerns and oil price rises and dependency promoted strong research in alternative fuel sources and vectors. Fischer-Tropsch products are considered a valid alternative to oil derivatives having the advantage of being able to share current infrastructures. As a renewable source of energy, synthesis gas obtained from biomass gasification presents itself as a sustainable alternative. However, prior to hydrocarbon conversion, the bio-syngas must be conditioned, which includes the removal of carbon dioxide for subsequent sequestration and capture. A pressure swing adsorption cycle was developed for the removal and concentration of CO₂ from the bio-syngas stream. Activated carbon was chosen as adsorbent. The simulation results showed that it was possible to produce a (H₂ + CO) product with a H₂/CO stoichiometric ratio of 2.14 (suitable as feed stream for the Fischer-Tropsch reactor) and a CO₂ product with a purity of 95.18%. A CO₂ recovery of 90.3% was obtained. A power consumption of 3.36 MW was achieved, which represents a reduction of about 28% when compared to a Rectisol process with the same recovery.     

生物质炭和富二氧化碳合成气制取二甲醚

研究了一种利用富二氧化碳合成气和生物质炭联合制取二甲醚的方法, 其过程包括两个步骤: 富二氧化碳合成气调整以及调整后合成气合成二甲醚. 在合成气调整过程中, 利用生物质炭为原料在Ni/Al₂O₃催化剂上将富二氧化碳合成气调整为富一氧化碳合成气. 经过800 °C合成气调整后, 合成气中CO₂含量大幅降低而CO含量大幅提高, CO₂/CO的摩尔比从原始合成气的6.33降至0.21. 然后, 分别用调整前后的合成气合成二甲醚, 结果表明, 经过调整后, C转化率得到很大的提高, 二甲醚产率比调整前高4倍. 本工作提供了一种可利用富二氧化碳生物质合成气制取燃料的途径, 并且提供了一种新的利用生物质炭的方法.     

Hydroformylation of alkenes with paraformaldehyde catalyzed by rhodium-phosphine complexes

The hydroformylation of medium-chain C6 olefins and of allyl alcohol was achieved with paraformaldehyde in dioxane solution using rhodium catalysts with mono-, bi-, and tri-dentate phosphine ligands. The highest activities with n/i ratios around 2, were obtained for a system derived from [Rh(dppe)₂]⁺, prepared in situ by reaction of Rh(acac)(CO)₂ with 2 eq of dppe.     

Ethylene and propylene polymerization with bis(indenyl)zirconium/Mao catalytic systems modified by sterically demanding alcohols

Ethylene and propylene polymerization using Ind₂ZrCl₂ and Ind₂Zr(CH₃)₂/MAO catalytic systems modified by the sterically demanding bridged alicyclic alcohols, adamantan‐1‐ol, adamantan‐2‐ol, 2‐methyladamantan‐2‐ol, and fenchyl alcohol, was investigated. Lower alcohols like isopropanol completely deactivate the system, whereas in the case of catalysts modified by these voluminous alcohols only a slight decrease in the catalytic activity proportional to alcohol/metallocene molar ratio was observed. The addition of the modifiers gives rise to polymers with higher molecular weights than the nonmodified systems, but no structural changes in the polyethylenes were observed. The addition of the sterically demanding alcohols to the reaction medium changes the regioregularity of polypropylenes, but does not significantly influence their stereoregularity, at 30 °C. Propylene–ethylene copolymers containing up to 8.6% of ethylene units derived from 1,3‐insertion and significant amount of rr‐centered pentads were obtained by single‐monomer polymerization of propylene with Ind₂ZrCl₂/MMAO/adamantan‐1‐ol, at 70 °C. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4248–4259, 2005     

Ce-Cu-Co/CNTs催化剂催化合成气制低碳醇及乙醇的研究

采用共浸渍法制备了不同Ce含量的Ce-Cu-Co/CNTs 催化剂, 考察了其在合成气制低碳醇反应中的催化性能, 借助X射线衍射(XRD)、程序升温还原(H₂-TPR)、N₂吸脱附实验(BET)、透射电镜(TEM)和CO程序升温脱附(CO-TPD)对这些催化剂进行了表征. 结果表明, 当Ce的质量分数为3%时, 低碳醇的时空收率和选择性达到最高, 分别为696.4 mg·g^-1·h^-1和59.7%, 其中乙醇占总醇的46.8%, 适量Ce的添加能提高Cu物种在催化剂上的分散度和催化剂的还原性能, 能显著地增加催化剂吸附CO的能力, 促进合成醇活性位的形成, 进而明显提高催化剂的活性和总醇的选择性. 研究表明, 将具有高活性和高碳链增长能力的CuCo基催化剂与碳纳米管的限域效应结合, 可实现缩窄产物分布、大幅度提高乙醇选择性的目的.     

Alcohol Oxidations Using Reduced Polyoxovanadates

A full account of our recently communicated room temperature alcohol oxidation using reduced polyoxovanadates (r‐POV s) is presented. Extensive optimizations revealed optimal conditions employing 0.02 equiv. of r‐POV catalyst Cs₅(V₁₄As₈O₄₂Cl), 5 equiv. tert‐butyl hydrogen peroxide (^t BuOOH ) as the terminal co‐oxidant, in an acetone solvent for the quantitative oxidation of aryl‐substituted secondary alcohols to their ketone products. The substrate scope tolerates most aryl substituted secondary alcohols in good to quantitative yields while alkyl secondary and primary activated alcohols were sluggish in comparison under similar conditions. Catalyst recyclability was successful on a 1.0 mmol scale of starting alcohol 1‐phenylethanol. The oxidation was also successfully promoted by the V^IV /V^V mixed valent polyoxovanadate (POV ) Cs₁₁Na₃Cl₅(V₁₅O₃₆Cl). Finally, a third POV , Cs_2.64(V₅O₉)(AsO₄)₂, was investigated for catalytic activity using our established reaction protocol, but proved ineffective as compared to the other two r‐POV catalysts. This study expands the field of POM ‐mediated alcohol oxidations to include underexplored r‐POV catalysts. While our catalysts do not supplant the best catalysts known for the transformation, their study may inform the development of other novel oxidative transformations mediated by r‐POV s.     

Radiochemical study of gas-phase reactions of diethylstannyl cations Et2SnT+ with oxygen-containing compounds: II. Reaction of diethylstannyl cations with butanol

Gas-phase reaction of nucleogenic diethylstannyl cations Et₂SnT⁺ with butan-1-ol has been studied by the radiochemcal method, and probable reaction mechanisms have been proposed. During the process diethylstannyl cations undergo isomerization into tertiary Me₂EtSn⁺ cations and rearrangement with elimination of ethane. Thermochemical parameters of reactions of diethyl-substituted cations derived from Group 14 elements (Et₂TM⁺; M = C, Si, Ge, Sn) with alcohols have been analyzed by the M06L aug-cc-pVDZ quantum chemical method.     

Liquid Phase Selective Oxidation of Alcohols over VPO Catalysts Supported on Mesoporous Hexagonal Molecular Sieves (HMS)

The vanadium phosphorous oxide (VPO) catalysts, supported on mesoporous hexagonal molecular sieves (HMS) with different vanadium loadings, were prepared by precipitation method on organic phase. Techniques such as XRD, BET and SEM, were used for characterization of the catalyst. The bulk VPO catalyst contains vanadyl pyrophosphate phase ((VO)₂P₂O₇), and a small amount of VOPO₄. The high surface area, large pore volume and pore size of HMS in VPO/HMS samples, provide an excellent dispersion of same phase of VPO compound on the support surface. Oxidation of various alcohols was studied in the liquid phase over VPO/HMS catalyst, using tert‐butylhydroperoxide (TBHP) as an oxidant. The activity of VPO/HMS samples were considerably increased with respect to bulk VPO catalyst. At 90 °C, the obtained activities were 0.567 and 6.545 g_pro.g^?1_VPOh^?1 over the bulk VPO and 20 wt% VPO/HMS catalysts, respectively. The effects of substrates, reaction time, reaction temperature, solvents, catalyst recycling and leaching of VPO in liquid phase reaction were also investigated. The following order has been observed for the percentage of conversions of alcohols: Benzylic alcohol > Secondary alcohol ～ Primary alcohol. The kinetic of benzyl alcohol oxidation using excess TBHP over VPO/HMS catalyst was investigated at temperatures of 27, 60 and 90 °C, and followed a pseudo‐first order with respect to benzyl alcohol.     

Polymerization of α-Hydroxyacetylenes by Transition Metal Catalysts

Abstract

α-Hydroxyacetylenes (2-propyn-1-ol, DL-3-butyn-2-ol, 1-octyn-3-ol, 2-phenyl-3-butyn-2-ol) with a hydroxy functional group were polymerized by various Mo- and W-based catalysts. In general, the catalytic activities of Mo-based catalysts were greater than those of W-based catalysts for these polymerizations. In the polymerization of 2-propyn-l-ol, MoCl₅ alone and the MoCl₅-EtAlCl₂ catalyst system gave a quantitative yield of polymer. In the polymerization of 2-propyn-l-ol and its homologues by Mo-based catalysts, the polymer yield decreased as the bulkiness of the substituent increased. On the other hand, the polymer yield increased as the bulkiness of the substituent increased in WCl₆-EtAlCl₂-catalyzed polymerization. Polymers with a bulkier substituent showed better solubility in organic solvents than those without a substituent [e.g., poly (2-propyn-l-ol)]. The structures of the resulting polymers were characterized by various instrumental methods such as ¹H- and ¹³C-NMR, IR, and UV-visible spectroscopies. Thermogravimetric analyses and thermal transitions of the resulting polymers were also studied.     

Preparation of Bio-hydrogen and Bio-fuels from Lignocellulosic Biomass Pyrolysis-Oil

In recent years, production of engine fuels and energy from biomass has drawn much interest. In this work, we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic biomass pyrolysis-oil (bio-oil). The process includes (i) the production of bio-hydrogen or bio-syngas by the catalytic cracking of bio-oil, (ii) the adjustment of bio-syngas, and (iii) the production of bio-fuels by ole nic polymerization (OP) together with Fischer-Tropsch synthesis (FTS). Under the optimal conditions, the yield of bio-hydrogen was 120.9 g H₂/(kg bio-oil). The yield of hydrocarbon bio-fuels reached 526.1 g/(kg bio-syngas) by the coupling of OP and FTS. The main reaction pathways (or chemical processes) were discussed based on the products observed and the catalyst property.     

Novel Catalysts for Gasification of Biomass with High Conversion Efficiency

We have developed catalysts for the gasification of biomass with much higher energy efficiency than the conventional methods (noncatalyst, dolomite, and commercial steam reforming Ni catalyst). In our investigation, the Rh/CeO₂ gave high yields of syngas for cellulose gasification using a fluidized-bed reactor with batch feeding of cellulose. However, the catalyst was deactivated because of sintering of CeO₂ during the reaction. To prevent the CeO₂ sintering, we have further improved the catalyst and found that Rh/CeO₂/SiO₂ was quite stable for the gasification of cellulose. It was demonstrated that Rh/CeO₂/SiO₂ gave almost complete gasification of real biomass (wood powder) at 873 K. These results indicate that the combination of this kind of catalyst and fluidized-bed reactor can realize the energy-efficient biomass gasification.     

Reactions of [CH3]+ and [CD3]+ with alcohols

The reactions of [CH₃]⁺ and [CD₃]⁺ with a number of C₁ to C₅ alcohols were studied at approximately thermal energies (0.1 eV) using a tandem Dempster ion cyclotron resonance mass spectrometer. Branching ratios obtained under single collision conditions are reported for [CH₃]⁺ and [CD₃]⁺ with methanol, perdeutero methanol, ethanol, allyl alcohol, 1-propanol, 2-propanol, perdeutero-2-propanol, 1-butanol, 2-butanol, t-butanol, cyclopentanol and 1-pentanol. The results are examined in terms of the mechanism of reactions and indicate that upon progression to larger alcohols, the formation of a long-lived adduct becomes less important in determining the reaction products.     

Application of ferrocenylimidazolium salts as catalysts for the transfer hydrogenation of ketones

Ferrocenylimidazolium salts with methylene and phenyl groups bridging the ferrocenyl and alkylimidazolium moieties were synthesized and characterized by spectroscopic and analytical methods. Crystal structures of two new compounds are also reported. Cyclic voltammetry was used to analyze the influence of the two bridging groups or spacers on electrochemical properties of the salts relative to the shifts in the formal electrode or peak potentials (E⁰ or E_1/2) of the ferrocene/ferrocenium redox couple. Results from this study showed that all the salts exhibited higher electrode potentials relative to ferrocene, which is due to the electron‐withdrawing effect of the imidazolium ion on the ferrocenyl moiety. Application of the salts as catalysts in transfer hydrogenation of ketones resulted in high conversion of saturated ketones to corresponding alcohols and turnover numbers as high as 1880. The catalysts were chemoselective towards reduction of the C═C bonds of conjugated 3‐penten‐2‐one and 4‐hexen‐3‐one to yield saturated ketones, while unconjugated 5‐hexen‐2‐one was hydrogenated to an unsaturated alcohol. Copyright © 2012 John Wiley & Sons, Ltd.     

不同碱处理制备多级孔HZSM-5催化剂及噻吩烷基化性能研究

用Na₂CO₃、TPAOH和TPA⁺/CO₃^2-混合碱分别处理HZSM-5分子筛,采用FT-IR、XRD、XRF、N₂吸附脱附、SEM、NH₃-TPD及Py-FTIR表征手段对各类碱处理前后的HZSM-5分子筛进行表征。结果表明,3种类型的碱处理HZSM-5分子筛后,均能形成微孔-介孔多级孔道的HZSM-5(A)催化剂,并能调变催化剂的酸性,其中,TPA⁺/CO₃^2-混合碱处理得到的HZSM-5(TPA⁺/CO₃^2-)催化剂,比表面积最大,介孔数量最多。在小型固定床反应器上,考察了HZSM-5和HZSM-5(A)催化剂的噻吩烷基化性能,结果表明,HZSM-5(TPA⁺/CO₃^2-)催化剂因为具有适当的多级孔孔道和较多的B酸中心而表现出较高的噻吩转化率和1-己烯对噻吩的选择性。     

微量Li助剂对Co/AC催化剂合成高碳醇性能的影响

采用等体积浸渍法制备了含微量Li 的15Co_xLi/AC 催化剂,考察了微量Li 助剂对15Co/AC催化剂上CO加氢合成高碳醇性能的影响. 采用X射线衍射、程序升温还原和程序升温表面反应技术对15Co_xLi/AC 催化剂进行了表征,结果表明,微量Li 的添加可以提高催化剂上CO加氢活性、生成C₅₊烃的选择性、合成醇的选择性以及高碳醇的分布. 这主要是由于微量Li 助剂与Co物种形成了弱相互作用,促进了催化剂Co物种的分散,形成较小Co晶粒,促进了Co₂C的形成.