固体碱催化剂上HDC的洁净合成

对由1，6-己二胺（HDA）和碳酸二甲酯（DMC）合成1，6-六亚甲基二氨基甲酸甲酯（HDC）的洁净化工艺过程进行了初步研究。考察了不同固体碱催化剂对该反应的催化活性，筛选出活性较高的MgO／ZrO2。通过考察MgO负载量的影响以及对该催化剂进行XRD表征，推断处于分散相的MgO催化活性高于晶相MgO。采用高效液相色谱（HPLC）对HDC进行定量分析，考察了不同反应条件时其催化性能的影响．     

负载型Zn(OAc)2催化合成1,6-六亚甲基二氨基甲酸甲酯

采用等体积浸渍法制备了一系列不同载体负载Zn(OAc)_2催化剂,用于1,6-己二胺(HDA)与碳酸二甲酯(DMC)反应制备1,6-六亚甲基二氨基甲酸甲酯(HDC)。通过X射线粉末衍射(XRD),N_2物理吸附(BET),NH_3程序升温脱附(NH_3-TPD),热重分析(TG-DTG),傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)对催化剂进行了表征,结果表明,硅胶负载Zn(OAc)_2催化剂上Si—O—Zn键的形成有利于DMC的活化,表面酸性位促进了碱性HDA的活化,从而使其具有最佳催化活性。在反应温度80℃、反应时间6 h、DMC/HDA摩尔比2∶1、催化剂用量n〔Zn(OAc)_2〕∶n(HDA)=0.02∶1的条件下,HDA转化率为96.0%,HDC收率可达68.5%,催化剂具有良好的稳定性,循环利用5次后活性无明显下降。     

Catalytic synthesis of toluene‐2,4‐diisocyanate from dimethyl carbonate

The process for catalytic synthesis of toluene‐2,4‐diisocyanate (TDI) from dimethyl carbonate (DMC) consists of two steps. Starting from the catalytic reaction between toluene‐2,4‐diamine (TDA) and DMC, dimethyl toluene‐2,4‐dicarbamate (TDC) is formed, and then decomposed to TDI. For the first step, the yield of TDC is 53.5% at a temperature of 250 °C, over Zn(OAc)₂/α–Al₂O₃ catalyst. For the second step, the yield of TDI is 92.6% at temperatures of 250–270 °C and under pressure of 2.7 kPa, over uranyl zinc acetate catalyst, when di‐n‐octyl sebacate(DOS) is used as heat‐carrier, and a mixture of tetrahydrofuran (THF) and nitrobenzene is used as solvent. © 2001 Society of Chemical Industry     

1,6-己二胺与氨基甲酸甲酯非均相CeO2催化合成1,6-己二氨基甲酸甲酯（英文）

The efficient synthesis of dimethylhexane-1,6-dicarbamate (HDC) from 1,6-hexanediamine (HDA) and methyl carbonate over a series of heterogeneous catalysts (e.g., MgO, Fe2O3, Mo2O3, and CeO2) was investigated. The reaction pathway was confirmed as an alcoholysis reaction through a series of designed experiments. Under optimized conditions, 100%HDA conversion with 83.1%HDCtotal and 16.9%polyurea was obtained using a one-step with high temperature procedure with CeO2 as the catalyst. A new two-step with variable temperature technol-ogy was developed based on the reaction pathway to reduce the polyurea yield. Using the proposed method, the HDCtotal yield reached 95.2%, whereas the polyurea yield decreased to 4.8%. The CeO2 catalyst showed high stability and did not exhibit any observable decrease in the HDC yield or any structural changes after four recycling periods. ? 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.     

Synthesis of dimethyl hexane-1,6-diyldicarbamate from 1,6-hexamethylenediamine and methyl carbamate using lead dioxide as catalyst

A series of metal oxides and lead compounds were employed as catalysts for the methoxycarbonylation of 1,6-hexamethylenediamine (HDA) with methyl carbamate (MC) to produce dimethyl hexane-1,6-diyldicarbamate (HDC). Lead-containing compounds showed excellent catalytic behavior, 100% conversion of HDA and 93% yield of HDC could be achieved with lead dioxide (PbO₂) as catalyst at 463 K for 6 h in the first cycle, then it goes down to 72%. The X-ray diffraction (XRD) and Infrared spectrum (IR) characterization results indicated that PbO₂ catalyst has been converted into lead carbonate (PbCO₃) through intermediate dilead oxide carbonate (Pb₂OCO₃) in the reaction process. This conversion may be the reason for the reduction of PbO₂ catalytic activity.     

Isomérisation du n‐hexane sur des catalyseurs Ni‐WOx/Al2O3‐SiO2

Isomerization of n‐hexane into bi‐ and tri‐branched products was studied at atmospheric pressure on Ni‐WO_x/Al₂O₃‐SiO₂ catalysts. Two groups of catalysts (A and B) were prepared by using the sol‐gel method. The objective of the present study is the selection of the catalyst having the best isomer (bi‐ and tri‐branched) yield under optimum operating conditions (reaction temperature, reduction temperature, flow duration, etc.). The results show that the introduction of tungsten (group B) modifies siginificantly the catalyst activity and that the optimum nickel amount in these catalysts is 15 wt. %. When a steady flow is achieved (100 min), the catalyst containing 15 % nickel and 10 % tungsten exhibits the highest and largest selectivity at a reaction temperature of 250°C and a reduction temperature of 430°C.     

Catalytic hydrothermal liquefaction of D. tertiolecta for the production of bio‐oil over different acid/base catalysts

In this article, two acid catalysts (ZrO₂/SO₄^2? and HZSM‐5) and two base catalysts (MgO/MCM‐41 and KtB) were used in catalytic hydrothermal liquefaction (HTL) of Dunaliella tertiolecta (D. tertiolecta) for the production of bio‐oil. The results indicated that the acid/base property of the catalyst plays a crucial role in the catalytic HTL process, and the base catalyst is conducive to the improvement of conversion and bio‐oil yield. When KtB was used as the catalyst, the maximum conversion and bio‐oil yield was 94.84 and 49.09 wt %, respectively. The detailed compositional analysis of the bio‐oil was performed using thermogravimetric analysis, elemental analysis, FT‐IR, and GC‐MS. The compositional analysis results showed that the introduction of catalyst is beneficial for reducing the fixed carbon content in the bio‐oil, and the structure of catalyst influences on the bio‐oil composition and boiling point distribution. Based on our results and previous studies, the probable catalytic HTL microalgae model over various catalysts can be described that the main chemical reactions include ketonization, decarboxylic, dehydration, ammonolysis, and so forth. with HZSM‐5 and MgO/MCM‐41 as the catalyst; the cyclodimerization, decomposition, Maillard reaction, and ketonization are the main reactions with ZrO₂/SO₄^2? as the catalyst; the dehydration, ammonolysis, Maillard reaction, and ketonization can occur with KtB as the catalyst. Therefore, a plausible reaction mechanism of the main chemical component in D. tertiolecta is proposed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1118–1128, 2015     

Polycarbonate polyurethane elastomers synthesized via a solvent‐free and nonisocyanate melt transesterification process

Soluble and thermally stable polycarbonate polyurethane elastomers were synthesized through a solvent‐free and nonisocyanate melt transesterification process. The conditions of this process were studied, and the optimum conditions were as follows: the catalyst dibutyltin oxide dosage was 0.125 wt %, the raw material molar (n) ratio of dimethyl 1,6‐hexamethylene dicarbamate (HDC) to poly(carbonate macrodiol) (PCDL) was n(HDC)/n(PCDL) = 1:0.99, the reactants were prepolymerized under 100°C for 1 h and then under 185°C and a high vacuum for 4 h. Three different PCDLs were selected to participate in the reaction under the conditions mentioned previously, and their structures were characterized by Fourier transform infrared spectroscopy and X‐ray diffraction. The products obtained from this process were still stable under 280°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41377.     

Structures and properties of polycarbonate modified polyether‐polyurethanes prepared by transurethane polycondensation

Thermoplastic polycarbonate modified polyether‐polyurethane (PEPU) elastomers were prepared by transurethane polycondensation method using poly(oxytetramethylene) glycol of M_n = 2000 and dimethyl‐hexane‐1,6‐dicarbamate as the main raw materials, 1,4‐butanediol as a chain extender and polycarbonate diol (PCDL) as an additive in the presence of dibutyltin oxide as a catalyst. The effect of the PCDL on the PEPUs' structure, intrinsic viscosity, molecular weight, mechanical, optical, and thermal properties, and water resistance were studied. The polycarbonate modified PEPUs showed better mechanical and thermal properties, but lower molecular weight and optical properties than the PEPUs. The PEPUs modified by PCDL1000 exhibited better performance, including mechanical, optical, and thermal properties, than those by PCDL2000. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42804.     

Studies on thermoplastic polyurethanes based on new diphenylethane‐derivative diols. III. The effect of molecular weight and structure of soft segment on some properties of segmented polyurethanes

Two series of poly(ether urethane)s and one series of poly(ester urethane)s were synthesized, containing, respectively, poly(oxytetramethylene) diol (PTMO) of M _n = 1000 and 2000 and poly(ε‐caprolactone) diol of M _n = 2000 as soft segments. In each series the same hard segment, i.e., 4,4′‐(ethane‐1,2‐diyl)bis(benzenethiohexanol)/hexane‐1,6‐diyl diisocyanate, with different content (～ 14–72 wt %) was used. The polymers were prepared by a one‐step melt polymerization in the presence of dibutyltin dilaurate as a catalyst, at the molar ratio of NCO/OH = 1 (in the case of the polymers from PTMO of M _n = 1000 also at 1.05). For all polymers structures (by FTIR and X‐ray diffraction analysis) and physicochemical, thermal (by differential scanning calorimetry and thermogravimetric analysis), and tensile properties as well as Shore A/D hardness were determined. The resulting polymers were thermoplastic materials with partially crystalline structures (except the polymer with the highest content of PTMO of M _n = 2000). It was found that the poly(ether urethane)s showed lower crystallinity, glass‐transition temperature (T_g), and hardness as well as better thermal stability than the poly(ester urethane)s. Poly(ether urethane)s also exhibited higher tensile strength (up to 23.5 MPa vs. 20.3 MPa) and elongation at break (up to ～ 1950% vs. 1200%) in comparison with the corresponding poly(ester urethane)s. Among the poly(ether urethane)s an increase in soft‐segment length was accompanied by an increase in thermal stability, tensile strength, and elongation at break, as well as a decrease in T_g, crystallinity, and hardness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A new catalytic process for high‐efficiency synthesis of p‐xylene by methylation of toluene with CH3Br

A new catalytic process for p‐xylene synthesis from the methylation of toluene with CH₃Br was proposed. CH₃Br was prepared from the catalytic bromination of natural gas (CH₄), by using H₂O + HBr + O₂ as mediator over supported Rh catalyst. The methylation conditions were investigated using HZSM‐5 or modified HZSM‐5 catalyst. Under optimal reaction conditions, p‐xylene selectivity is up to 93%, and p‐xylene yield is more than 21% at 673 k over the Si—P modified HZSM‐5 catalyst. Compared to the processes using MeOH or dimethyl carbonate (DMC) as methylation agent, this new process is very attractive in an economic standpoint since CH₄ is much cheaper than MeOH and DMC. In addition, the process has other advantages, such as mild reaction conditions, simple operation, high‐product yield, and so on. It is predicted that the process has good industrial potential for para‐xylene production. © 2012 American Institute of Chemical Engineers AIChE J, 59: 532–540, 2013     

1,6-己二氨基甲酸酯合成的研究进展

综述了1,6-己二氨基甲酸酯（HDC）合成所用的羰基化试剂及其相关的各类催化剂。对CO、CO2、碳酸二甲酯（DMC）和氨基甲酸酯等羰基化试剂合成HDC的优缺点进行了系统评述。指出氨基甲酸酯的低毒、高活性、来源广等优点使其发展为合成HDC最具工业化前景的羰基化试剂;同时对碳酸二甲酯和氨基甲酸酯制备HDC的催化剂进行了介绍、分类、评述和总结,以期为开发高效HDC合成催化剂提供指导。最后表明制备廉价、易分离回收和循环利用的环境友好催化剂是推动HDC产业化的关键。     

Ring‐opening copolymerization of maleic anhydride with propylene oxide by double‐metal cyanide

Ring‐opening copolymerization of maleic anhydride (MA) with propylene oxide (PO) was successfully carried out by using double‐metal cyanide (DMC) based on Zn₃[Co(CN)₆]₂. The characteristics of the copolymerization are presented and discussed in this article. The structure of the copolymer was characterized with IR and ¹H‐NMR. Number‐average molecular weight (M_n) and molecular weight distribution (MWD) of the copolymer were measured by GPC. The results showed that DMC was a highly active catalyst for copolymerization of MA and PO, giving high yield at a low catalyst level of 80 mg/kg. The catalytic efficiency reached 10 kg polymer/g catalyst. Almost alternating copolymer was obtained when monomer charge molar ratio reached MA/PO ≥ 1. The copolymerization can be also carried out in many organic solvents; it was more favorable to be carried in polar solvents such as THF and acetone than in low‐polarity solvents such as diethyl ether and cyclohexane. The proper reaction temperature carried in the solvents was between 90 and 100 °C. The M_n was in the range of 2000–3000, and it was linear with the molar ratio of conversion monomer and DMC catalyst. The reactivity ratio of MA and PO in this reaction system was given by the extended Kelen–Tudos equation: η=[r₁+(r₂/α)]ξ?(r₂/α) at some high monomer conversion. The value of reactivity ratio r₁(MA) = 0 for MA cannot be polymerized itself by DMC catalyst, and r₂(PO) = 0.286. The kinetics of the copolymerization was studied. The results indicated that the copolymerization rate is first order with respect to monomer concentration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1788–1792, 2004     

Polymerization of acrylonitrile catalyzed by single yttrium tris(2,6‐di‐tert‐butyl‐4‐methyl phenolate)

Polymerization of acrylonitrile was carried out using yttrium tris(2,6‐di‐tert‐butyl 4‐methyl‐phenolate) (Y(OAr)₃) as single component catalyst for the first time. The effects of concentrations of the monomer and catalyst, kinds of rare earth element and solvent, as well as temperature and polymerization time were investigated. The overall activation energy of polymerization in n‐hexane and THF mixture is 18.3 kJ mol^?1. Polyacrylonitriles (PANs) obtained by using Y(OAr)₃ in n‐hexane and THF mixture at 50 °C are predominantly atactic, while yellow PANs obtained in DMF under the same conditions have a syndiotactic‐rich configuration (>50%), and their highly branched and/or cyclized structures have also been found. © 2002 Society of Chemical Industry     

Non-phosgene synthesis of hexamethylene-1,6-diisocyanate from thermal decomposition of hexamethylene-1,6-dicarbamate over Zn–Co bimetallic supported ZSM-5 catalyst

A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 catalyst.The catalyst was characterized by FTIR and XRD analyses. Three solvents dioctyl sebacate(DOS), dibutyl sebacate(DBS) and 1-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_4) were investigated and compared; DOS gave better performance. The catalytic performances for thermal decomposition of HDC to HDI using DOS as solvent were then investigated, and the results showed that, under the optimized reaction conditions, i.e.,10 wt%concentration of HDC in DOS, 250 °C temperature, 60 min reaction time, 83.8% yield of HDI had been achieved over Zn–Co/ZSM-5. Decomposition of the intermediate hexamethylene-1-carbamate-6-isocyanate(HMI) over Zn–Co/ZSM-5 in DOS solvent was further studied and the results indicated that yield of HDI from HMI reached to 69.6%(98.6% HDI selectively) at 270 °C, which further increased the yield of the total HDI(HDI_(tol)) to as high as 95.0%. Recycling of catalyst showed that HDI and HMI yield slightly decreased, and by-product yield increased after the catalyst was reused for 4 times. At last possible reaction mechanism was proposed.     

Modulating morphology and textural properties of ZrO2 for supported Ni catalysts toward dry reforming of methane

This work presents a facile and efficient approach to modulate morphology and textural properties of ZrO₂ through ammonium fluoride‐urea assisted hydrothermal (FUAH) method with diverse parameters including molar ratio of NH₄F to zirconium (n_f/z), molar ratio of urea to zirconium (n_u/z), hydrothermal temperature (T_hydroth), and hydrothermal time (t_hydroth), which serve as support for supported Ni catalysts toward dry reforming of methane (DRM) to produce synthesis gas. The plausible mechanism for forming ZrO₂ supports with different morphologies under diverse hydrothermal conditions was proposed. Various characterization techniques were employed to investigate the effect of preparation parameters on the morphology and textural properties of the as‐synthesized ZrO₂ supports, as well as to reveal the structure‐performance relationship of the Ni/ZrO₂ catalysts prepared by L‐arginine assisted incipient wetness impregnation method toward DRM reaction. The developed supported Ni catalyst on hierarchically structured ZrO₂ with pinecone shape prepared by FUAH method (Ni/ZrO₂‐FUAH) demonstrates higher activity and stability for DRM than that on ZrO₂ prepared by traditional hydrothermal method (Ni/ZrO₂‐H). The higher activity of Ni/ZrO₂‐FUAH than Ni/ZrO₂‐H can be ascribed to the higher Ni dispersion, smaller Ni crystalline size, and enhanced reducibility of NiO, significantly affected by morphology of support, as well as the higher coke‐resistance catalytic stability can be ascribed to smaller Ni particle size and stronger Ni‐support interaction, strongly dependent on morphology and textural properties of ZrO₂ supports that affected by FUAH process parameters. The outstanding catalytic performance of the developed Ni/ZrO₂‐FUAH catalyst allows it to be a promising candidate for synthesis gas production through DRM reaction. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2900–2915, 2017     

Efficient synthesis of 1,6-hexamethylene diurethane through coupling transesterification and methoxycarbonylation with methyl phenyl carbonate as intermediate

A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate (MPC) as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane (HDU) from 1,6-hexamethylene diamine (HDA). The feasibility of the system was explored using the thermodynamics analysis, the reaction mechanism and the experiment results. The optimal reaction was carried out to get higher HDU yield. The thermodynamic analysis showed that the methoxycarbonylation of HDA with MPC, the Gibbs free energy of which was negative, was a spontaneous process. Furthermore, the equilibrium constant of the methoxycarbonylation of HDA with MPC was much greater than that of the transesterification of dimethyl carbonate (DMC) with phenol, so the reaction coupling could be realized under mild conditions. The reaction mechanism analysis indicated that phenoxy anion was the key species for reaction coupling. Higher MPC concen-tration was detected when sodium phenoxide was used as transesterification reactant with DMC, since the phenoxy anion of sodium phenoxide could be dissociated more easily. Sodium phenoxide was more suitable to prepare HDU through reaction coupling. A yield of HDU as high as 98.3%could be reached under the optimal con-ditions of mPhONa/mDMC=0.027 and nDMC/nHDA=8/1 at 90 °C in 2 h.     

Rhodium‐Catalyzed Asymmetric Pauson–Khand Reaction Using Monophosphoramidite Ligand SIPHOS

A novel rhodium‐catalyzed asymmetric intramolecular Pauson–Khand reaction using a chiral monophosphoramidite ligands is described. In this reaction, an in situ generated catalyst from [Rh(CO)₂Cl]₂, the spiro‐monophosphoramidite ligand SIPHOS and AgSbF₆ was found to be effective for a series of 1,6‐enynes, providing the co‐cyclization products in good enantioselectivities (84% ee).     

Synthesis of Dimethyl Carbonate from Methyl Carbamate and Methanol Using a Fixed‐Bed Reactor

Several mixed oxide catalysts were prepared by coprecipitation for dimethyl carbonate (DMC) synthesis from methyl carbamate and methanol. During the batch process, the DMC yield was below 35 %. In order to minimize the unfavorable thermodynamic equilibrium and side reactions for the DMC synthesis, a fixed‐bed reactor was designed. A maximum DMC yield of ～ 73 % could be realized over a ZnO‐Al₂O₃ catalyst. The effects of reaction conditions for this type of reactor were investigated in detail.     

Comparison of supercritical CO2 and hexane extraction of lipids from sorghum distillers grains

Total yields and compositions of sorghum dried distillers grains with solubles (DDGS) lipids obtained by supercritical CO₂ (SC‐CO₂) extraction were compared with those obtained by recirculated solvent extraction (RSE) with hexane. The total yield of lipids obtained by SC‐CO₂ extraction at 27.5 MPa and 70 °C was 150 g lipids/kg DDGS, while the yield obtained by RSE with hexane at 69 °C was only 85 g lipids/kg DDGS. The contents of four high‐value compounds, i.e., policosanols, phytosterols, free fatty acids (FFA) and tocols, in the lipids obtained by SC‐CO₂ extraction were 31.2, 15.6, 155.3 and 0.50 mg/g at 27.5 MPa and 70 °C, compared to 26.6, 9.6, 57.3 and 0.03 mg/g for RSE with hexane at 69 °C. The profiles of phytosterols and FFA in the sorghum DDGS lipids were relatively independent of the extraction methods and operating conditions.