醋酸低级醇酯系列产品的合成及催化剂

本文概述了醋酸低级醇酯产品的用途和市场趋势及原料醋酸的生产现状,重点介绍了醋酸低级醇酯系列产品的不同合成方法及其特点,并对所用催化剂的特点及制备技术进行了综述。

Amine-grafted on lanthanide metal-organic frameworks:Three solid base catalysts for Knoevenagel condensation reaction

A post-synthetic modification strategy has been used to prepare three solid base catalysts, including Er（btc）（ED）075（H2O）0.25 （2, btc = 1,3,5-benzenetricarboxylates, ED = 1,2-ethanediamine）, Er（btc）（PP）0.55（H20）0.45 （3, PP = piperazine）, and Er（btc）（DABCO）0.15（H2O）0.85 （4, DABCO = 1,4- diazabicyclo[2.2.2]octane）, by grafting three different diamines onto the coordinatively unsaturated Er（III） ions into the channels of the desolvated lanthanide metal-organic framework （Er（otc））. The resulting metal-organic frameworks were characterized by elemental analysis, thermogravimetric analysis, powder X-ray diffraction, and N2 adsorption. Based on its higher loading ratio of the diamine, as well as its greater stability and porosity, catalyst 2 exhibited higher catalytic activity and reusability than catalysts 3 and 4- for the Knoevenagel condensation reaction. The catalytic mechanism of 2 has also been investigated using size-selective catalysis tests.

Advances in Application of Non-aqueous Phase Enzymatic Catalysis in Food Additive Production

Non-aqueous phase enzymatic catalysis technology has been widely ap- plied in the area of food additives production. This paper reviewed the types of re- action medium of non-aqueous phase enzymatic catalysis reaction, introduced the application of non-aqueous phase enzymatic catalysis technology in catalysis of L-ascorbic （isoascorbic） acid esters, short-chain acid esters, sugar esters, vitamin A esters, vi- tamin E esters, and other food additives, and finally predicted the prospects of non- aqueous phase enzymatic catalysis technology.

Bio-methanol from Bio-oil Reforming Syngas Using Dual-reactor

A dual-reactor, assembled with the on-line syngas conditioning and methanol synthesis, was successfully applied for high efficient conversion of rich CO2 bio-oil derived syngas to bio-methanol. In the forepart catalyst bed reactor, the catalytic conversion can effectively adjust the rich-CO2 crude bio-syngas into the CO-containing bio-syngas using the CuZnA1Zr catalyst. After the on-line syngas conditioning at 450℃, the CO2/CO ratio in the blo- syngas significantly decreased from 6.3 to 1.2. In the rearward catalyst bed reactor, the conversion of the conditioned bio-syngas to bio-methanol shows the maximum yield about 1.21 kg/（kgcatarh） MeOH with a methanol selectivity of 97.9% at 260 ~C and 5.05 MPa using conventional CuZnA1 catalyst, which is close to the level typically obtained in the conventional methanol synthesis process using natural gas. The influences of temperature, pressure and space velocity on the bio-methanol synthesis were also investigated in detail.

Production of Mixed Alcohols from Bio-syngas over Mo-based Catalyst

A series of Mo-based catalysts prepared by sol-gel method using citric acid as complexant were successfully applied in the high efficient production of mixed alcohols from bio-syngas, derived from the biomass gasification. The Cu1Co1Fe1MO1Zn0.5-6%K catalyst exhibited a higher activity on the space-time yield of mixed alcohols, compared with the other Mobased catalysts. The carbon conversion significantly increases with rising temperature below 340 ℃, but the alcohol selectivity has an opposite trend. The maximum mixed alcohols yield derived from biomass gasification is 494.8 g/（kg catal·h） with the C2＋ （C2-C6 higher alcohols） alcohols of 80.4% under the tested conditions. The alcohol distributions are consistent with the Schulz-Flory plots, except methanol. In the alcohols products, the C2＋ alcohols （higher alcohols） dominate with a weight ratio of 70%-85%. The Mo-based cata- lysts have been characterized by X-ray diffraction and N2 adsorption/desorption. The clean bio-fules of mixed alcohols derived from bio-syngas with higher octane values could be used as transportation fuels or petrol additives.

A review of significant factors in the synthesis of hetero-structured dumbbell-like nanoparticles

This paper reviews several important factors that influence the synthesis of dumbbell‐like nanoparticles,which can significantly enhance the catalyst activity in catalytic combustion. The dumbbell‐like nanoparticles discussed in this article refer to a hetero‐structure with two nanoparticles of different materials in contact with each other. This nanostructure can be considered as a special intermediate between individual spherical nanoparticles and a core–shell nanostructure. Therefore,the synthesis of dumbbell‐like nanoparticles is more difficult than other structures. The controllability of the synthesis process, the nanoparticle size and size distribution, and the morphology of the final products depend on many factors： the seed size and size ratio could be used to influence the controllability of epitaxial growth. The component sizes and size distribution could be varied by carefully controlling the reaction temperature and reaction time. The morphology of the dumbbell‐like nanoparticles is closely related to the solvent polarity, the precursor ratio, the lattice mismatch between the two components, and the surfactant concentration. Some related synthesis methods are also briefly introduced in each section to facilitate understanding. This summary will benefit the development of new dumbbell‐like nanoparticles with various components, which have great potential in catalytic combustion of more dysoxidizable gases.

Effects of Co_3O_4 nanocatalyst morphology on CO oxidation:Synthesis process map and catalytic activity

This study focuses on drawing a hydrothermal synthesis process map for Co3O4 nanoparticles with various morphologies and investigating the effects of Co3O4 nanocatalyst morphology on CO oxidation.A series of cobalt-hydroxide-carbonate nanoparticles with various morphologies（i.e.,nanorods,nanosheets,and nanocubes） were successfully synthesized,and Co3O4 nanoparticles were obtained by thermal decomposition of the cobalt-hydroxide-carbonate precursors.The results suggest that the cobalt source is a key factor for controlling the morphology of cobalt-hydroxide-carbonate at relatively low hydrothermal temperatures（≤ 140℃）.Nanorods can be synthesized in CoCl2 solution,while Co（NO3）2 solution promotes the formation of nanosheets.Further increasing the synthesis temperature（higher than 140 ℃） results in the formation of nanocubes in either Co（NO3）2 or CoCl2 solution.The reaction time only affects the size of the obtained nanoparticles.The presence of CTAB could improve the uniformity and dispersion of particles.Co3O4 nanosheets showed much higher catalytic activity for CO oxidation than nanorods and nanocubes because it has more abundant Co^（3＋） on the surface,much higher reducibility,and better oxygen desorption capacity.

Preparation of Fe-Mn/K/Al2O3 Fischer-Tropsch Catalyst and Its Catalytic Kinetics for the Hydrogenation of Carbon Monoxide

A K promoted iron-manganese catalyst was prepared by sol-gel method,and subsequently was tested for hydrogenation of carbon monoxide to light olefins.The kinetic experiments on a well-characterized Fe-Mn/K/Al2O3 catalyst were performed in a fixed-bed micro-reactor in a temperature range of 280-380 ℃,pressure range of 0.1-1.2 MPa,H2/CO feed molar ratio range of 1-2.1 and a space velocity range of 2000-7200 h-1.Considering the mechanism of the process and Langmuir-Hinshelwood-Hogan-Watson（LHHW） approach,unassisted CO dissociation and H-assisted CO dissociation mechanisms were defined.The best models were obtained using non-linear regression analysis and Levenberg-Marquardt algorithm.Consequently,4 models were considered as the preferred models based on the carbide mechanism.Finally,a model was proposed as a best model that assumed the following kinetically relevant steps in the iron-Fischer-Tropsch（FT） synthesis：（1） CO dissociation occurred without hydrogen interaction and was not a rate-limiting step;（2） the first hydrogen addition to surface carbon was the rate-determining steps.The activation energy and adsorption enthalpy were calculated 40.0 and -30.2 kJ.mol-1,respectively.

The relationship between the microstructures and catalytic behaviors of iron–oxygen precursors during direct coal liquefaction

A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°C.The relationship between the microstructures and catalytic activities of these precursors during direct coal liquefaction was studied.The results show that the microstructure could be controlled through adjusting the synthesis temperature during the precipitation‐oxidation procedure,and that compounds synthesized at lower temperatures exhibit higher catalytic activity.As a result of their higher proportions ofγ‐FeOOH orα‐FeOOH crystalline phases,the unsupported iron–oxygen compounds synthesized at 20–30°C,which also had high specific surface areas and moisture levels,generate oil yields 4.5%–4.6%higher than those obtained with precursors synthesized at 70°C.It was also determined that higher oil yields were obtained when the catalytically‐active phase formed by the precursors during liquefaction(pyrrhotite,Fe1-xS)had smaller crystallites.Feed coal added as a carrier was found to efficiently disperse the active precursors,which in turn significantly improved the catalytic activity during coal liquefaction.

Highlights of the major progress in single-atom catalysis in 2015 and 2016

The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in H2.The last six years have witnessed tremendous progress in the field of single‐atom catalysis.Here we introduce the major achievements on this topic in2015and2016.Some particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in electrochemistry.These accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.

Hybrid enzyme catalysts synthesized by a de novo approach for expanding biocatalysis

The two major challenges in industrial enzymatic catalysis are the limited number of chemical reaction types that are catalyzed by enzymes and the instability of enzymes under harsh conditions in industrial catalysis.Expanding enzyme catalysis to a larger substrate scope and greater variety of chemical reactions and tuning the microenvironment surrounding enzyme molecules to achieve high enzyme performance are urgently needed.In this account,we focus on our efforts using the de novo approach to synthesis hybrid enzyme catalysts that can address these two challenges and the structure-function relationship is discussed to reveal the principles of designing hybrid enzyme catalysts.We hope that this account will promote further efforts toward fundamental research and wide applications of designed enzyme hybrid catalysts for expanding biocatalysis.

Study on methanol synthesis from coal-based syngas

The intrinsic kinetic models of the Langmuir-Hinshelwood type were investigated in terms of the reaction rates of CO hydrogenation and CO_2 hydrogenation in theform of reactant fugacity. The parameters were estimated by the Universal Global Optimization using the Marquardt method. Residual error distribution and statistic tests show thatthe intrinsic kinetic models are reliable and acceptable. The mathematic model of a combined converter formed by gas-cooled and water-cooled reactor was developed and thegas-cooled reactor and the water-cooled reactor were characterized with one-dimensionalmathematic model. The distributions of temperature and concentration in the catalytic bedof the gas-cooled reactor and the water-cooled reactor in a combined converter with ayield of 1.2 Mt/a were simulated. The parallel cross linking pore model was used to describe the transfer process of multi-component diffusion system in the catalyst. The calculated value computed by the internal diffusion efficiency factor calculation model established for methanol synthesis catalyst fit the experimental value very well.

An Integrated Process of a Two-Stage Fixed Bed Syngas Production and F-T Synthesis for GTL in Remote Gas Field

A novel process for catalytic oxidation of methane to synthesis gas (syngas), which consists of two consecutive fixed-bed reactors with air introduced into the reactors, integrated Fischer-Tropsch synthesis, was investigated. At the same time, a catalytic combustion technology has been investigated for utilizing the F-T offgas to generate heat or power energy. The results show that the two-stage fixed reactor process keep away from explosion of CH4/O2. The integrated process is fitted to produce diesel oil and lubricating oil in remote gas field.

Effect of Cu-ZnO-Al_2O_3 supported on H-ferrierite on hydrocarbons formation from CO hydrogenation

Methanol synthesis catalysts based on Cu, Zn and Al were prepared by three methods and subsequently mixed with H-ferrierite zeolite in an aqueous suspension to disperse the catalysts over the support. These materials were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature programmed reduction, NH3 and H2 temperature-programmed desorption, and X-ray photoelectron spectroscopy. They were also applied to the CO hydrogenation reaction to produce dimethyl ether and hydrocarbons. The catalysts were prepared by coprecipitation under low and high supersaturation conditions and by a homogeneous precipitation method. The preparation technique was found to affect the precursor structural characteristics, such as purity and crystallinity, as well as the particle size distribution of the resulting catalyst. Low supersaturation conditions favored high dispersion of the Cu species, increasing the methanol synthesis catalyst＇s metallic surface area and resulting in a homogeneous particle size distribution. These effects in turn were found to modify the zeolite properties, promoting both a low micropore volume and blockage of the zeolite acid sites. The effect of the methanol synthesis catalyst on the reaction was verified by the correlation between the Cu surface area and the CO conversion rate.

Optimization of conditions for preparation of ZSM-5@silicalite-1 core–shell catalysts via hydrothermal synthesis

Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.

Propane Dehydrogenation over PtSnNa Catalyst Supported on La-ZSM-5 Zeolite

The La-ZSM-5 zeolite with different contents of La was synthesized by the hydrothermal method. The physico-chemical properties of the materials were studied. The results of FT-IR analyses indicated that La might be incorporated into the framework of ZSM-5 zeolite. The NH3-TPD analyses showed that the amount of weak acid sites of the zeolite decreased with a continuously increasing La content. Afterwards, the La-ZSM-5 zeolite was used as the support of PtSnNa catalyst for propane dehydrogenation. The test results revealed that the utilization of La- ZSM-5 zeolite could achieve a high propene conversion, and effectively inhibit the coke formation on the catalyst surface. When the content of La was 0.16%, the catalytic activity and stability of the catalyst got the best of its performance. Besides, the PtSnNa/La （0.16%）-ZSM-5 catalyst is more stable than the conventional PtSnNaLal ZSM-5 catalysts.

Effects of Reaction Conditions on Performance of Ru Catalyst and Iron Catalyst for Ammonia Synthesis

Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared,and the influences of reaction temperature,space velocity,pressure,and H2/N2 ratio on performance of iron catalyst coupled with Ru catalyst in series for ammonia synthesis were investigated.The activity tests were also performed on the single Ru and Fe catalysts as comparison.Results showed that the activity of the Ru catalyst for ammonia synthesis was higher than that of the iron catalyst by 33.5%-37.6% under the reaction conditions：375-400 °C,10 MPa,10000 h-1,H2︰N2 3,and the Ru catalyst also had better thermal stability when treated at 475 °C for 20 h.The outlet ammonia concentration using Fe-Ru catalyst was increased by 45.6%-63.5% than that of the single-iron catalyst at low tem-perature （375-400 °C）,and the outlet ammonia concentration increased with increasing Ru catalyst loading.

Study on the Carbon-Methanation and Catalytic Activity of Ru/AC for Ammonia Synthesis

The effects of promoters K, Ba, Sm on the resistance to carbon-methanation and catalytic activity of ruthenium supported on active carbon (Ru/AC) for ammonia synthesis have been studied by means of TG-DTG (thermalgravity-differential thermalgravity), temperature-programmed desorption, and activity test. Promoters Ba,K, and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly. Much higher activity can be reached for Ru/AC catalyst with bi- or tri-promoters. Indeed, the triply promoted catalyst showed the highest activity, coupled to a surprisingly high resistance to methanation. The ability of resistance of promoter to methanation of Ru/AC catalyst is dependent on the adsorption intensity of hydrogen. The strong adsorption of hydrogen would enhance methanation and impact the adsorption of nitrogen, which results in the decrease of catalytic activity.

Synthesis and characterization of Cu-Cr-O nanocomposites

Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP(ammonium perchlorate)-based solid-state propellants were synthesized via a citric acid(CA) complexing approach. Techniques of TG-DTA, XRD as well as TEM were employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced after the CA-Cu-Cr precursors are calcined at 500 ℃ for 3 h. Phase composition of the as-obtained Cu-Cr-O nanocomposites depends on the molar ratio of Cu to Cr in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid-state propellants considerably. Noticeably, catalyst with a CuCr molar ratio of 0.7 exhibits promising catalytic activity with high burning rate and low pressure exponent at all pressures, due to the effective phase interaction between the spinel CuCr2O4 and delafossite CuCrO2 contained in the as-synthesized Cu-Cr-O nanocomposites.

A facile solvent-free synthesis strategy for Co-imbedded zeolite-based Fischer-Tropsch catalysts for direct gasoline production

A series of Co-imbedded zeolite-based catalysts were synthesized following a facile solvent-free grinding route.The catalytic performance for direct syngas conversion to gasoline range hydrocarbons was compared with their counterpart Co-impregnated zeolite-based catalysts.Successful transformation of solid raw materials to targeted zeolite was confirmed by XRD,SEM,STEM,and N2 physisorption analysis.An in-depth study of acidic strength and acidic site distribution was conducted by NH3-TPD and Py-IR spectroscopy.Acidic strength showed a pivotal role in defining product range.Co@S1,with the weakest acidic strength of silicalite-1 among three types of zeolites,evaded over-cracking of product and exhibited the highest gasoline and isoparaffin selectivity(≈70%and 30.7%,respectively).Moreover,the solvent-free raw material grinding route for zeolite synthesis accompanies several advantages like the elimination of production of wastewater,high product yield within confined crystallization space,and elimination of safety concerns regarding high pressure due to the absence of the solvent.Facileness and easiness of the solvent-free synthesis route together with promising catalytic performance strongly support its application on the industrial scale.