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noble metal nanoparticle size on C–N bond cleavage performance in hydrodenitrogenation: a study of active

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 1986-2000 doi: 10.1007/s11705-023-2337-5

摘要： Breakage of the C–N bond is a structure sensitive process, and the catalyst size significantly affects its activity. On the active metal nanoparticle scale, the role of catalyst size in C–N bond cleavage has not been clearly elucidated. So, Ru catalysts with variable nanoparticle sizes were obtained by modulating the reduction temperature, and the catalytic activity was evaluated using 1,2,3,4-tetrahydroquinoline and o-propylaniline with different C–N bond hybridization patterns as reactants. Results showed a 13 times higher reaction rate for sp3-hybridized C–N bond cleavage than sp2-hybridized C–N bond cleavage, while the reaction rate tended to increase first and then decrease as the catalyst nanoparticle size increased. Different concentrations of terrace, step, and corner sites were found in different sizes of Ru nanoparticles. The relationship between catalytic site variation and C–N bond cleavage activity was further investigated by calculating the turnover frequency values for each site. This analysis indicates that the variation of different sites on the catalyst is the intrinsic factor of the size dependence of C–N bond cleavage activity, and the step atoms are the active sites for the C–N bond cleavage. When Ru nanoparticles are smaller than 1.9 nm, they have a strong adsorption effect on the reactants, which will affect the catalytic performance of the Ru catalyst. Furthermore, these findings were also confirmed on other metallic Pd/Pt catalysts. The role of step sites in C–N bond cleavage was proposed using the density function theory calculations. The reactants have stronger adsorption energies on the step atoms, and step atoms have d-band center nearer to the Fermi level. In this case, the interaction with the reactant is stronger, which is beneficial for activating the C–N bond of the reactant.

关键词： sp3/sp2-hybridized C–N bond     noble metal nanoparticle     catalytic active site     turnover frequency     DFT    

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Solid-state NMR for metal-containing zeolites: From active sites to reaction mechanism

Xingling Zhao, Jun Xu, Feng Deng

《化学科学与工程前沿（英文）》 2020年 第14卷 第2期   页码 159-187 doi: 10.1007/s11705-019-1885-1

摘要： Metal-containing zeolite catalysts have found a wide range of applications in heterogeneous catalysis. To understand the nature of metal active sites and the reaction mechanism over such catalysts is of great importance for the establishment of structure-activity relationship. The advanced solid-state NMR (SSNMR) spectroscopy is robust in the study of zeolites and zeolite-catalyzed reactions. In this review, we summarize recent developments and applications of SSNMR for exploring the structure and property of active sites in metal-containing zeolites. Moreover, detailed information on host-guest interactions in the relevant zeolite catalysis obtained by SSNMR is also discussed. Finally, we highlight the mechanistic understanding of catalytic reactions on metal-containing zeolites based on the observation of key surface species and active intermediates.

关键词： metal-containing zeolites     solid-state NMR     active site     host-guest interaction     reaction mechanism    

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Insights into carbon-based materials for catalytic dehydrogenation of low-carbon alkanes and ethylbenzene

《化学科学与工程前沿（英文）》 2023年 第17卷 第11期   页码 1623-1648 doi: 10.1007/s11705-023-2328-6

摘要： Direct dehydrogenation with high selectivity and oxidative dehydrogenation with low thermal limit has been regarded as promising methods to solve the increasing demands of light olefins and styrene. Metal-based catalysts have shown remarkable performance for these reactions, such as Pt, CrOx, Co, ZrOx, Zn and V. Compared with metal-based catalysts, carbon materials with stable structure, rich pore texture and large surface area, are ideal platforms as the catalysts and the supports for dehydrogenation reactions. In this review, carbon materials applied in direct dehydrogenation and oxidative dehydrogenation reactions including ordered mesoporous carbon, carbon nanodiamond, carbon nanotubes, graphene and activated carbon, are summarized. A general introduction to the dehydrogenation mechanism and active sites of carbon catalysts is briefly presented to provide a deep understanding of the carbon-based materials used in dehydrogenation reactions. The unique structure of each carbon material is presented, and the diversified synthesis methods of carbon catalysts are clarified. The approaches for promoting the catalytic activity of carbon catalysts are elaborated with respect to preparation method optimization, suitable structure design and heteroatom doping. The regeneration mechanism of carbon-based catalysts is discussed for providing guidance on catalytic performance enhancement. In addition, carbon materials as the support of metal-based catalysts contribute to exploiting the excellent catalytic performance of catalysts due to superior structural characteristics. In the end, the challenges in current research and strategies for future improvements are proposed.

关键词： carbon materials     dehydrogenation     active sites     mechanism     catalytic performance     support    

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Catalytic combustion of methane over a highly active and stable NiO/CeO

Xiuhui Huang, Junfeng Li, Jun Wang, Zeqiu Li, Jiayin Xu

《化学科学与工程前沿（英文）》 2020年 第14卷 第4期   页码 534-545 doi: 10.1007/s11705-019-1821-4

摘要： In the last decades, many reports dealing with technology for the catalytic combustion of methane (CH ) have been published. Recently, attention has increasingly focused on the synthesis and catalytic activity of nickel oxides. In this paper, a NiO/CeO catalyst with high catalytic performance in methane combustion was synthesized via a facile impregnation method, and its catalytic activity, stability, and water-resistance during CH combustion were investigated. X-ray diffraction, low-temperature N adsorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, hydrogen temperature programmed reduction, methane temperature programmed surface reaction, Raman spectroscopy, electron paramagnetic resonance, and transmission electron microscope characterization of the catalyst were conducted to determine the origin of its high catalytic activity and stability in detail. The incorporation of NiO was found to enhance the concentration of oxygen vacancies, as well as the activity and amount of surface oxygen. As a result, the mobility of bulk oxygen in CeO was increased. The presence of CeO prevented the aggregation of NiO, enhanced reduction by NiO, and provided more oxygen species for the combustion of CH . The results of a kinetics study indicated that the reaction order was about 1.07 for CH and about 0.10 for O over the NiO/CeO catalyst.

关键词： methane combustion     NiO/CeO2 catalyst     interaction     oxygen vacancy     kinetic study    

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Influence of site conditions on seismic design parameters for foundations as determined via nonlinearsite response analysis

Muhammad Tariq A. CHAUDHARY

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 275-303 doi: 10.1007/s11709-021-0685-0

摘要： Site conditions, including geotechnical properties and the geological setting, influence the near-surface response of strata subjected to seismic excitation. The geotechnical parameters required for the design of foundations include mass density ( ), damping ratio ( ), shear wave velocity ( ), and soil shear modulus ( ). The values of the last three parameters are sensitive to the level of nonlinear strain induced in the strata due to seismic ground motion. In this study, the effect of variations in soil properties, such as plasticity index ( ), effective stress ( ), over consolidation ratio (OCR), impedance contrast ratio ( ) between the bedrock and the overlying strata, and depth of soil strata over bedrock ( ), on seismic design parameters ( , , and ) was investigated for National Earthquake Hazards Reduction Program (NEHRP) site classes C and D, through 1D nonlinear seismic site response analysis. The Morris one-at-a-time (OAT) sensitivity analysis indicated that , , and were significantly influenced by variations in , while affected more than it affected and . However, the influence of on these parameters was less significant. It was also found that variations in soil properties influenced seismic design parameters in soil type D more significantly than in soil type C. Predictive relationships for , , and were derived based on the 1D seismic site response analysis and sensitivity analysis results. The , , and values obtained from the analysis were compared with the corresponding values in NEHRP to determine the similarities and differences between the two sets of values. The need to incorporate and in the metrics for determining , , and for the seismic design of foundations was highlighted.

关键词： site effects     1D seismic site response analysis     sensitivity analysis     foundations     shear wave velocity     soil shear modulus    

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Tuning of the active phase structure and hydrofining performance of alumina-supported tri-metallic WMoNi

Shufeng Shan, Haiyan Liu, Gang Shi, Xiaojun Bao

《化学科学与工程前沿（英文）》 2018年 第12卷 第1期   页码 59-69 doi: 10.1007/s11705-017-1686-3

摘要： The effects of phosphorus on the structure and hydrofining performance of tri-metallic WMoNi/Al O catalysts prepared with W/Mo-based hybrid precursor nanocrystals were investigated. The incorporation of phosphorus weakened the metal-support interactions (MSIs) and facilitated the formation of more synergetic NiWMoS phases with higher stacks. Catalytic tests using a fluid catalytic cracking diesel fuel showed that the changes in the MSIs and the morphology of the active phases had a more positive effect on the hydrodenitrogenation activity than on the hydrodesulfurization activity. In contrast, when phosphorus was incorporated into a tri-metallic WMoNiP/Al O catalyst prepared by a conventional incipient impregnation method, the MSIs decreased causing aggregation of the metal species which resulted in poorer hydrofining performance of the catalyst. These results show that incorporating phosphorus into a WMoNi/Al O catalyst can finely tune the structure of the active phase to enhance the hydrogenation and hydrodenitrogenation activity of the resulting tri-metallic catalyst.

关键词： fluid catalytic cracking diesel     hydrofining performance     WMoNiP/Al2O3     synergetic effect and structure of NiWMoS phases    

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Microemulsion-mediated hydrothermal synthesis of flower-like MoS

Yuxia Jiang, Donge Wang, Zhendong Pan, Huaijun Ma, Min Li, Jiahe Li, Anda Zheng, Guang Lv, Zhijian Tian

《化学科学与工程前沿（英文）》 2018年 第12卷 第1期   页码 32-42 doi: 10.1007/s11705-017-1677-4

摘要： Flower-like intercalated MoS nanomaterials have been successfully synthesized via a microemulsion-mediated hydrothermal (MMH) method, and characterized by X-ray diffraction, Raman spectroscopy, element analysis, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy in detail. Their catalytic performance for anthracene hydrogenation was evaluated using a slurry-bed batch reactor with an initial hydrogen pressure of 80 bar at 350 °C for 4 h. The intercalated MoS nanoflowers synthesized from Na MoO (MoS -S) and H MoO (MoS -A) as molybdenum precursors have diameters of about 150 and 50 nm, respectively. MoS nanosheets on MoS -S and MoS -A possess stacking layer numbers of 5–10 and 2–5, and slab lengths of about 15 and 10 nm, respectively. The interlayer distances of MoS -S and MoS -A are both enlarged from 0.62 nm to about 0.95 nm due to the intercalation of NH and surfactant molecules. The MoS nanoflowers have high catalytic activities for anthracene hydrogenation. The selectivity for octahydroanthracene, a deeply hydrogenated product, over MoS -A is 89.8%, which is 31.0 times higher than that over commercial bulk MoS . Fully hydrogenated product (perhydroanthracene) was also detected over MoS nanoflowers with a selectivity of 3.7%. The enhanced hydrogenation activities of MoS nanoflowers can be ascribed to the high exposure of catalytic active sites, resulting from the smaller particle size, fewer stacking layer, shorter slab length and enlarged interlayer distance of MoS nanoflowers compared with commercial bulk MoS . In addition, a possible growth mechanism of MoS nanoflowers synthesized via the MMH method was proposed.

关键词： microemulsion     intercalated MoS2     catalytic hydrogenation     active sites    

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Development and application of an off-site maintenance system in the petrochemical industry

Ruisheng YONG, Yanbing YE, Hanbin LUO, Lieyun DING

《工程管理前沿（英文）》 2017年 第4卷 第2期   页码 111-126 doi: 10.15302/J-FEM-2017027

摘要： On-site maintenance (ONSM) is critical to ensuring the safety of equipment in the petrochemical industry. However, many accidents occur during ONSM processes because of unstable equipment, complicated work environment, and human error. To reduce congestion and exposure to hazards during on-site operations and thereby reduce the probability of accidents, off-site maintenance (OFSM) is proposed based on Energy Release Theory (ERT). The information requirements for OFSM are analyzed. A support system for OFSM, which makes use of visualization, information management, and localization capabilities, is developed. A case study utilizing OFSM and its support system for an oil-loading facility of a petrochemical company is conducted. The application results indicated that implementation of OFSM system can significantly reduce the operation risks and can improve the operation efficiency.

关键词： on-site maintenance     petrochemical industry     safety     off-site maintenance system    

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behavior of Co3O4 on HZSM-5 support: designing applicable catalysts for selective catalytic

《化学科学与工程前沿（英文）》 2023年 第17卷 第11期   页码 1741-1754 doi: 10.1007/s11705-023-2332-x

摘要： Based on monolayer dispersion theory, Co3O4/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia. Co3O4 can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m–2, equaling to a weight percentage around 4.5%. It has been revealed that the quantities of surface active oxygen (O2–) and acid sites are crucial for the reaction, which can adsorb and activate NOx and NH3 reactants effectively. Below the monolayer dispersion threshold, Co3O4 is finely dispersed as sub-monolayers or monolayers and in an amorphous state, which is favorable to generate the two kinds of active sites, hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide. However, the formation of crystalline Co3O4 above the capacity is harmful to the reaction performance. 4% Co3O4/ZSM-5, the catalyst close to the monolayer dispersion capacity, possesses the most abundant active O2– species and acidic sites, thereby demonstrating the best reaction performance in all the samples. It is proposed the optimal Co3O4/ZSM-5 catalyst can be prepared by loading the capacity amount of Co3O4 onto HZSM-5 support.

关键词： Co3O4/ZSM-5     NOx-SCR by NH3     monolayer dispersion threshold effect     surface acid sites     surface active O2– anions    

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雅砻江普斯罗坝址深部裂缝带成因的探讨

李玶,李愿军,杨美娥,赵东芝

《中国工程科学》 2007年 第9卷 第3期   页码 11-20

摘要：

雅砻江普斯罗坝址在工程勘探过程中，发现了深部裂缝带，裂缝带位于１００～２００m深处，与地表有 巨厚的完整岩体相隔，产状与该区的一组NE向断裂基本一致；断层物质的最新形成年龄为２畅７～９万年，裂缝 面上有水平、斜向和上下擦痕，表明深部裂缝带可能是断裂带新活动的结果。断裂新活动所产生的地震波，受 到疏松破碎带的阻挡，导致深部裂缝带出现。这一成因机制，在地下核爆炸和岩石动力学的试验观测中有所证实。

关键词： 雅砻江普斯罗坝址     深部裂缝带     卸荷和重力滑塌     活断层    

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An integrated approach to site-specific management zone delineation

Yuxin MIAO, David J. MULLA, Pierre C. ROBERT

《农业科学与工程前沿（英文）》 2018年 第5卷 第4期   页码 432-441 doi: 10.15302/J-FASE-2018230

摘要：

Dividing fields into a few relatively homogeneous management zones (MZ) is a practical and cost-effective approach to precision agriculture. There are three basic approaches to MZ delineation using soil and/or landscape properties, yield information, and both sources of information. The objective of this study is to propose an integrated approach to delineating site-specific MZ using relative elevation, organic matter, slope, electrical conductivity, yield spatial trend map, and yield temporal stability map (ROSE-YSTTS) and evaluate it against two other approaches using only soil and landscape information (ROSE) or clustering multiple year yield maps (CMYYM). The study was carried out on two no-till corn-soybean rotation fields in eastern Illinois, USA. Two years of nitrogen (N) rate experiments were conducted in Field B to evaluate the delineated MZs for site-specific N management. It was found that in general the ROSE approach was least effective in accounting for crop yield variability (8.0%–9.8%), while the CMYYM approach was least effective in accounting for soil and landscape (8.9%–38.1%), and soil nutrient and pH variability (9.4%–14.5%). The integrated ROSE-YSTTS approach was reasonably effective in accounting for the three sources of variability (38.6%–48.9%, 16.1%–17.3% and 13.2%–18.7% for soil and landscape, nutrient and pH, and yield variability, respectively), being either the best or second best approach. It was also found that the ROSE-YSTTS approach was effective in defining zones with high, medium and low economically optimum N rates. It is concluded that the integrated ROSE-YSTTS approach combining soil, landscape and yield spatial-temporal variability information can overcome the weaknesses of approaches using only soil, landscape or yield information, and is more robust for MZ delineation. It also has the potential for site-specific N management for improved economic returns. More studies are needed to further evaluate their appropriateness for precision N and crop management.

关键词： economically optimum nitrogen rate     fuzzy cluster analysis     precision nitrogen management     site-specific management     soil landscape property     yield map    

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Site-directed mutagenesis of long QT syndrome KCNQ1 gene

LI Wei, WANG Bin, XU Qiumei, KE Qinmei, YANG Junguo, DU Rong, TIAN Li, WANG Qing

《医学前沿（英文）》 2008年 第2卷 第1期   页码 100-104 doi: 10.1007/s11684-008-0018-x

摘要： To construct a polymerase chain reaction (PCR) site-directed mutagenesis of the long QT syndrome KCNQ1 gene , two sets of primers were designed according to the sequence of KCNQ1 cDNA and a mismatch was introduced into primers. Mutagenesis was performed in a two-step PCR. The amplified fragments from the third PCR which contained the mutation site were sub-cloned into the T-vector pCR2.1. Then, the fragments containing the mutation site was obtained from pCR2.1 using restriction enzymes digestion and inserted into the same restriction site of pIRES-EGFP-KCNQ1. The sequencing analysis shows that the mutation site was correct. Mutation from A to G in site 983 of KCNQ1 cDNA was found. Using the Effectene transfection reagent, pIRES-EGFP-KCNQ1 (G983A) was transfected into HEK cells successfully. These results may shed light on further functional study of KCNQ1 gene.

关键词： restriction     digestion     syndrome     sequence     site-directed mutagenesis    

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Construction Technology of Off-Site Precast Concrete Buildings

Ting Gong,Jian Yang,Hao Hu,Feng Xu

《工程管理前沿（英文）》 2015年 第2卷 第2期   页码 122-124 doi: 10.15302/J-FEM-2015039

摘要： The industrialization of building construction is gradually becoming a new choice of construction technology driven by some great advantages such as high efficiency in construction, low energy consumption and environmental friendliness. Construction management plays an important part to ensure the quality of projects. A comparison between traditional on-site and modern off-site construction methods has been conducted. The streamlining of the process including the fabrication, transportation, stacking and assembling of precast components has also been analyzed with a discussion on the BIM application in the process.

关键词： off-site construction     precast concrete     modular construction     construction management     building information model (BIM)    

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Evaluation of site response characteristic using nonlinear method (Case study: Babol, Iran)

Asskar Janalizadeh CHOOBBASTI, Sadegh REZAEI, Farzad FARROKHZAD, Pedram Haidarzaeh AZAR

《结构与土木工程前沿（英文）》 2014年 第8卷 第1期   页码 69-82 doi: 10.1007/s11709-014-0231-4

摘要： In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data and synthesis of drilling data extracted from the Babol’s subsurface database have enabled authors to determine the geotechnical properties of each site. These data are consisted of twenty five boreholes up to depth of 40 m. Based on the obtained data from geotechnical investigation the study area is divided to five zones. Dynamic analysis was performed in time domain, using fully nonlinear model by PLAXIS. A series of analysis in the study area showed the site period, ranging from 0.4 to 0.8 s. Finally the obtained response spectra from fully nonlinear method were compared with site response spectra of Iran’s 2800 (earthquake) code.

关键词： fully nonlinear method     site effect     dynamic analysis     response spectra    

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A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

Sainab Omar, Yang Yang, Jiawei Wang

《化学科学与工程前沿（英文）》 2021年 第15卷 第1期   页码 4-17 doi: 10.1007/s11705-020-1933-x

摘要： This review article summarizes the key published research on the topic of bio-oil upgrading using catalytic and non-catalytic supercritical fluid (SCF) conditions. The precious metal catalysts Pd, Ru and Pt on various supports are frequently chosen for catalytic bio-oil upgrading in SCFs. This is reportedly due to their favourable catalytic activity during the process including hydrotreating, hydrocracking, and esterification, which leads to improvements in liquid yield, heating value, and pH of the upgraded bio-oil. Due to the costs associated with precious metal catalysts, some researchers have opted for non-precious metal catalysts such as acidic HZSM-5 which can promote esterification in supercritical ethanol. On the other hand, SCFs have been effectively used to upgrade crude bio-oil without a catalyst. Supercritical methanol, ethanol, and water are most commonly used and demonstrate catalyst like activities such as facilitating esterification reactions and reducing solid yield by alcoholysis and hydrolysis, respectively.

关键词： bio-oil     upgrading     supercritical     review    

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标题 作者 时间 类型 操作

noble metal nanoparticle size on C–N bond cleavage performance in hydrodenitrogenation: a study of active

期刊论文

Solid-state NMR for metal-containing zeolites: From active sites to reaction mechanism

Xingling Zhao, Jun Xu, Feng Deng

期刊论文

Insights into carbon-based materials for catalytic dehydrogenation of low-carbon alkanes and ethylbenzene

期刊论文

Catalytic combustion of methane over a highly active and stable NiO/CeO

Xiuhui Huang, Junfeng Li, Jun Wang, Zeqiu Li, Jiayin Xu

期刊论文

Influence of site conditions on seismic design parameters for foundations as determined via nonlinearsite response analysis

Muhammad Tariq A. CHAUDHARY

期刊论文

Tuning of the active phase structure and hydrofining performance of alumina-supported tri-metallic WMoNi

Shufeng Shan, Haiyan Liu, Gang Shi, Xiaojun Bao

期刊论文

Microemulsion-mediated hydrothermal synthesis of flower-like MoS

Yuxia Jiang, Donge Wang, Zhendong Pan, Huaijun Ma, Min Li, Jiahe Li, Anda Zheng, Guang Lv, Zhijian Tian

期刊论文

Development and application of an off-site maintenance system in the petrochemical industry

Ruisheng YONG, Yanbing YE, Hanbin LUO, Lieyun DING

期刊论文

behavior of Co3O4 on HZSM-5 support: designing applicable catalysts for selective catalytic

期刊论文

雅砻江普斯罗坝址深部裂缝带成因的探讨

李玶,李愿军,杨美娥,赵东芝

期刊论文

An integrated approach to site-specific management zone delineation

Yuxin MIAO, David J. MULLA, Pierre C. ROBERT

期刊论文

Site-directed mutagenesis of long QT syndrome KCNQ1 gene

LI Wei, WANG Bin, XU Qiumei, KE Qinmei, YANG Junguo, DU Rong, TIAN Li, WANG Qing

期刊论文

Construction Technology of Off-Site Precast Concrete Buildings

Ting Gong,Jian Yang,Hao Hu,Feng Xu

期刊论文

Evaluation of site response characteristic using nonlinear method (Case study: Babol, Iran)

Asskar Janalizadeh CHOOBBASTI, Sadegh REZAEI, Farzad FARROKHZAD, Pedram Haidarzaeh AZAR

期刊论文

A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

Sainab Omar, Yang Yang, Jiawei Wang

期刊论文