检索结果-南通市图书馆

三江源国家公园居民生计恢复力的驱动因素研究：基于PLS-SEM和fs/QCA（英文）

在线全文

学校读者我要写书评

暂无评论

Journal of Resources and Ecology 2024年第5期15卷 1274-1285页

作者：卜诗洁王群胡昌伟卓玛措安徽师范大学地理与旅游学院澳门城市学院国际旅游与管理学院青海民族大学旅游学院

本文旨在探讨旅游发展感知、适应能力和转型能力对国家公园居民生计恢复力的影响。以中国三江源国家公园黄河源园区为例，采用偏最小二乘法结构方程模型（PLS-SEM）和模糊集定性比较分析方法（fs/QCA），探寻各变量之间的线性和非线性... 详细信息

本文旨在探讨旅游发展感知、适应能力和转型能力对国家公园居民生计恢复力的影响。以中国三江源国家公园黄河源园区为例，采用偏最小二乘法结构方程模型（PLS-SEM）和模糊集定性比较分析方法（fs/QCA），探寻各变量之间的线性和非线性动态影响。PLS-SEM结果显示，适应能力和转型能力对生计恢复力具有正向影响；旅游发展感知对生计恢复力具有负向影响，但对适应能力和转型能力有正向影响；旅游发展感知和适应能力可以通过转型能力对生计恢复力产生正向影响。fs/QCA结果表明，单一的前因变量均不构成居民生计恢复力的必要条件，各变量需要依赖与其他变量的组合共同作用；确定了高生计恢复力的2条组态路径和导致低生计恢复力的3条组态路径，其中，适应能力和转型能力是引发高生计恢复力的关键因素，旅游发展感知则是造成低生计恢复力的重要因素。

关键词：生计恢复力旅游发展感知适应能力转型能力 fs/QCA 三江源国家公园

Molybdenum carbide as catalyst in biomass derivatives conversion

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第10期31卷 68-87,I0003页

作者： Xiangze Du Rui Zhang Dan Li changwei hu Hermenegildo Garcia Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengdu 610064SichuanChina Instituto Universitario de Tecnología Química Consejo Superior de Investigaciones Científicas.-Universitat Politecnica de ValenciaUniversitat Politecnica de ValenciaAv.De los Naranjos s/nValencia 46022Spain Department of Chemistry University of HelsinkiA.I.Virtasen Aukio 1P.O.Box 5500014Finland

The present energy dilemma in conjunction with the adverse environmental impacts caused by fossil fuel combustion motivates researchers to seek for new renewable energy with minimal CO_(2)*** a practice pathway,it is of significance to produce biofuel and platform chemicals from sustainable biomass ***,the research and development of high-efficiency catalysts remain one key scientific *** the catalysts developed,transition metal carbides,especially molybdenum carbide,show promising performances on biomass-based *** efforts have been made in past few decades on tuning the structure and electronic property of molybdenum carbide via controlling particle size and morphology,metal and nonmetal doping and vacancies,*** review summarizes recent developments of molybdenum carbide as catalysts in converting biomass into fuel,mainly focused on the preparation methods,the structure-dependent effects and the electronic *** controllable selective cleavage of C-C,C-O and C-H bonds over modified molybdenum carbides that has been demonstrated in the conversion of biomass feedstocks is then *** addition,the possible deactivation mechanisms of molybdenum carbide are also presented in the *** review provides systematic and fundamental information for the further design and development of molybdenum carbide for the conversion of biomass resources.

关键词： Molybdenum carbide Synthesis Modification Hydrogenation Biomass Selective cleavage

Room temperature pretreatment of pubescens by AlCl_3 aqueous solution

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2019年第4期28卷 138-147页

作者： Yue Wang Xiaoyan Lv Jindong Li Qiuxing Li changwei hu Key Laboratory of Green Chemistry and Technology Ministry of Education College of Chemistry Sichuan University College of Chemical Engineering Sichuan University

Room temperature(about 16°C)pretreatment of pubescens by Al Cl_3aqueous solution with different concentrations was *** the presence of 20 wt%Al Cl_3for pretreatment within 24 h,the degradation of hemicellulose reached 19.5 wt%without obvious degradation of cellulose and lignin(2.7 wt%and2.4 wt%,respectively).The extracted hemicellulose from pubescens could be divided into two parts,i.e.,small molecular weight products(saccharides and carboxylic acid,which occupy approximately 28.2%)and oligomers(approximately 71.8%).Low concentration of AlCl_3(<10 wt%)slightly promoted the formation of oligomers with molecular weight in the range of 200–1000 Da,while high concentration of Al Cl_3(10–20 wt%)promoted the formation of oligomers in the molecular weight range above 20,000 *** conversion of hemicellulose with acceptable selectivity resulted in the cleavage of bond between hemicellulose and lignin yielding three classical Lignin-Carbohydrate complexes.

关键词： AlCl3 Pretreatment Pubescens Hemicellulose Lignin-Carbohydrate complex(LCC)

Effects of vanadium(V)-substitution on the oxidative properties of α-Keggin-type heteropolyanion clusters——progress in DFT theoretical studies

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2009年第12期52卷 2096-2105页

作者： WANG JinYue FU XiaoHong WANG Jian hu changwei Institute of Applied Chemistry Department of Chemistry and Chemical EngineeringKey Laboratory of Computational Physics in Universities of SichuanYibin UniversityYibin 644007China Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengdu 610064China

The redox properties of α-Keggin-type heteropolyanion clusters [XM12O40]n-(X = Si,P; M = Mo,W) mainly depend on their constituent outer metal-oxygen cages {M12O36}. They act as "reservoirs",through which the transfer and transition of electrons and protons may occur. At the atomic and molecular level,the redox properties of these clusters can be controlled and also tuned by modifying the metal M in the cages and the central heteroatom X of the clusters. Combined with relevant experimental results,this review summarizes our recent theoretical investigations of the effect of vanadium substitution on the redox properties of Keggin anion clusters. Theoretical modeling and calculation results showed that the oxidative ability of the modified species was increased by partial substitution of the cage M atoms of the Keggin clusters by vanadium atoms which have lower electronegativity. A linear correlation between the catalytic efficiency per vanadium atom and the microstructures of the vanadium(V)-substituted heteropolyanions [PVnMo12-nO40](3+n)-(n = 1-3) was established for the first time. This relationship may be suitable to interpret the catalytic behavior of the title compounds in the hydroxylation of benzene to phenol,and may also be used in understanding other reactions such as the oxidative dehydrogenation of isobutyric acid and the nitration of adamantine. The establishment of this nearly linear structure-property relationship may lay the foundations of understanding the behavior of the title compounds in homogeneous catalytic oxidation reactions,and may direct the design of future catalysts and the choice of other catalytic reactions.

关键词： polyoxometalates α-Keggin-type heteropolyanions vanadium substitution oxidative property density functional theory (DFT)

The Promotion Effect of NaCl on the Conversion of Xylose to Furfural

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2020年第2期38卷 178-184页

作者： Zheng Li Yiping Luo Zhicheng Jiang Qianying Fang changwei hu Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengduSichuan 610064China College of Materials and Chemistry&Chemical Engineering Chengdu University of TechnologyChengduSichuan 610059China National Engineering Laboratory for Clean Technology of Leather Manufacture Sichuan UniversityChengduSichuan 610065China

Summary of main observation and conclusion In this work,the promotion effect of NaCl on the conversion of xylose to furfural in H2O was *** was found that xylose conversion and furfural yield increased with NaCl *** decreased the pH of the solution providing H+ for the acid catalytic dehydration of *** formation of oligomers was determined by GPC and ESI-MS in the initial stage of reaction,especially at low *** NaCl promoted the formation of humins in the late stage of the *** could also change the decomposition route of formic ***,NaCl had the ability of phase *** these effects with organic solvent during the reaction could inhibit the formation of humins and increase the yield of *** NaCl-H2O-THF biphasic system without other catalyst,the optimal furfural yield of 76.7% and selectivity of 77.6% were achieved at 463 K in 2 h.

关键词： temperature. reaction. conclusion

Efficient catalytic conversion of jatropha oil to high grade biofuel on Ni-Mo_(2)C/MCM-41 catalysts with tuned surface properties

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2021年第10期30卷 425-435,I0012页

作者： Xiangze Du Keyao Zhou Linyuan Zhou Xiaomei Lei huiru Yang Dan Li changwei hu Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengdu 610064SichuanChina

The activity of Mo_(2) C-based catalyst on vegetable oil conversion into biofuel could be greatedly promoted by tuning the carbon content,while its modification mechanism on the surface properties remained ***,the exposed active sites,the particle size and Lewis acid amount of Ni-Mo_(2) C/MCM-41 catalysts were regulated by varying CH_(4) content in carbonization *** activity of Ni-Mo_(2) C/MCM-41 catalysts in jatropha oil(JO)conversion showed a volcano-like trend over the catalysts with increasing CH_(4) content from 15%to 50%in the preparation *** one prepared by 25%CH_(4) content(NiMo_(2) C(25)/MCM-41)exhibited the outstanding catalytic performance with 83.9 wt%biofuel yield and95.2%C_(15)-C_(18) *** a variation of activity was ascribed to the most exposed active sites,the smallest particle size,and the lowest Lewis acid amount from Ni^(0) on the Ni-Mo_(2) C(25)/MCM-41 catalyst ***,the Ni-Mo_(2) C(25)/MCM-41 catalyst could also effectively catalyze the conversion of crude waste cooking oil(WCO)into green *** study offers an effective strategy to improve catalytic performance of molybdenum carbide catalyst on vegetable oil conversion.

关键词： Ni-Mo_(2)C/MCM-41 catalyst Carbonization Jatropha oil Crude waste cooking oil Green diesel

Selective extraction and conversion of lignin in actual biomass to monophenols: A review

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2016年第6期25卷 947-956页

作者： Zhicheng Jiang changwei hu Key Laboratory of Green Chemistry and Technology Ministry of Education College of Chemistry Sichuan University

Our over dependency on the fossil resource for industrial chemicals and fuels faces great challenges. Recently, the production of monophenols from lignin in lignocellulosic biomass is regarded as a promising process for sustainable biofuels. This article discusses the conversion of lignin in actual biomass directly to monophenols. The two step way including extraction of lignin from biomass and further degradation of the lignin oligomers to monophenols is especially discussed. The obtained monophenols can also be converted to chemicals with low-oxygen content via hydrodeoxygenation process. For extraction of lignin, co-solvent system is the most adopted for hydrolysis or solvolysis of lignin assisted by acid or alkaline catalysts. The structure of the obtained oligomers derived from lignin is discussed in detail. For lignin depolymerization, hydrogenolysis is an efficient method with the use of gaseous hydrogen or alcohols as hydrogen source. At the meantime, depolymerization mechanism and the route for repolymerization of the reaction intermediates are presented here. In hydrodeoxygenation process, metal catalysts, especially noble metal catalysts are required. The precise effects of the reaction solvents and catalysts on extraction and degradation of lignin need to be further investigated, and this will benefit to design more efficient strategies for lignin utilization. © 2016 Science Press

关键词： Biomass Catalysts Extraction Hydrolysis Industrial chemicals Oligomers Precious metals Reaction intermediates Reviews Solvents

Recent advances for the production of hydrocarbon biofuel via deoxygenation progress

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2015年第24期60卷 2096-2106页

作者： Dan Li hui Xin Xiangzhe Du Xiaolei Hao Qingxue Liu changwei hu Key Laboratory of Green Chemistry and Technology Ministry of Education College of Chemistry Sichuan University College of Chemical Engineering Sichuan University

The current world energy crisis and increasing environmental concerns over global climate change from combusting fossil fuel are driving researchers into a new route to produce fuels via sustainable resource to meet the demands of human. In recent years, deoxygenation as an alternative method has been applied in the production of hydrocarbon fuels, particularly via the deoxygenation of fatty acids and triglycerides from seed oils and fats, producing hydrocarbon fuels entirely fungible with fossil fuels. The deoxygenation of biobased feedstock to fuel-like hydrocarbons is critically reviewed in this article. The review mainly discusses the use of feedstock, innovation of catalysts, and the reaction mechanism involved in the production of hydrocarbon fuels via deoxygenation progress.

关键词： Deoxygenation Biobased feedstock -Hydrocarbon fuels Deoxygenation mechanism

Catalytic pyrolysis of Pubescens to phenols over Ni/C catalyst

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2010年第7期53卷 1487-1491页

作者： LUO Jia LI Jie SHEN DanFeng HE Ling TONG DongMei hu changwei Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengdu 610064China

The pyrolysis of Pubescens over Ni/C catalyst was studied at 350°C in H2 *** presence of Ni/C catalyst efficiently improved the degradation of raw materials,and produced bio-oil with high content of phenols but low contents of acetic acid,furfural and *** the reaction,Ni/C catalyst plays the role of catalytic decomposition and catalytic *** existence of the carbon carrier favors the formation of active Ni in small sizes with more defects,which results in high catalytic activity of Ni in biomass decomposition and selective production of phenols.

关键词： Ni/C catalyst Pubescens catalytic pyrolysis phenols