Organic‐free synthesis of MOR nanoassemblies with excellent DME carbonylation performance

Seed‐assisted low alkalinity gel system was developed to explore the organic‐free synthesis of MORzeolite.MOR nanoassemblies with Si/Al ratio(SAR)up to 9.4 and high solid yield(84–94%)weresuccessfully obtained under controlled low alkalinity conditions.Characterization results demonstratethat the acid strength increases in parallel with the SAR,while the total acid amount and theproton distribution in the main channels and the side pockets are similar for the samples.The protondistribution in the H‐MOR is not straightforwardly related to the Na+distribution in theas‐synthesized MOR,implying the transfer of the protons among the oxygen sites of framework Tatom.Relative to low‐silica samples I‐5.3 and I‐7.4,sample I‐9.4 displays the best mass transferperformance and accessibility of the acid sites by pyridine due to its relatively low Al density andmild dealumination degree.Correspondingly,sample I‐9.4(pyridine‐modified catalyst)shows thebest activity with ca.100%selectivity of methyl acetate(MAc)in the DME carbonylation reaction.The high steady MAc yield(6.8 mmol/g/h)over sample I‐9.4 suggests the promising application ofMOR nanoassemblies synthesized by this economical organic‐free strategy.

Thermodynamic Analysis and Synthesis Gas Generation by Chemical-Looping Gasification of Biomass with Nature Hematite as Oxygen Carriers

Thermodynamic parameters of chemical reactions in the system were carried out through thermodynamic analysis. According to the Gibbs free energy minimization principle of the system, equilibrium composition of the reactions of chemical-looping gasification (CLG) of biomass with natural hematite (Fe2O3) as oxygen carrier were analyzed using commercial software of HSC Chemistry 5.1. The feasibility of the CLG of biomass with hematite was experimental verified in a lab-scale bubbling fluidized bed reactor using argon as fluidizing gas. It was indicated the experimental results were consistent with the theoretical analysis. The presence of oxygen carrier gave a significant effect on the biomass conversion and improved the synthesis gas yield obviously. It was observed that the gas content of CO and H2 was over 70% in CLG of biomass. The reduced hematite particles mainly existed in form of FeO. It was showed that the reduction of natural hematite with biomass proceeds in a stepwise manner from Fe2O3 →Fe3O4→ FeO. Reduction product of natural hematite can be restored the lattice oxygen by oxidation with air.

A biomass gasification system for synthesis gas from the new method

This paper describes a single fluidized bed by the two-step gasification of the working method, process and biomass and coal co-gasification by a certain proportion of the results of a typical run. The results show that the biomass gasifi-cation technology for raw materials has a wide adaptability, the tar content in the gas is less than 10mg/m3,component in it ,the H2+CO>70%, H2/C ≈1~2,especially suitable for biomass from hydrogen, synthetic alcohol fuel, is a promising approach.

Progress and Prospect of Single-step Synthesis of DME

Patents and previous research concerning the single-step synthesis of DME were reviewed. Rapid deactivation of the bifunctional catalyst is the main issue for the commercialization of the single-step synthesis process; in addition, the separation process and utilization of by-products have a larger impact on economic performance of the process. Recent progress involving the development of bifunctional catalysts and separation technology in the single-step process will most likely make the process commercially available in the near future.

Simple and High-Yield Synthesis of a Thinner Layer of Graphenic Carbon from Coconut Shells

Biomass has become of recent interest as a raw material for‘green’graphenic carbon(GC)since it promotes an environmentally friendly approach.Here,we investigate a single pyrolysis route to synthesize GC from coconut shells which provides a simple method and can produce a high yield,thus being convenient for large-scale pro-duction.The pyrolysis involves a stepped holding process at 350℃ for 1 h and at 650℃ or 900℃ for 3 h.The GC sample resulted at the 900℃ pyrolysis has a thinner sheet,a less porous structure,a higher C/O ratio,and an enhanced electrical conductivity than those pyrolyzed at 650℃.The addition of Na3PO4 catalyst has no signifi-cant effects on the GC structures obtained by this route.The single pyrolysis route generates thinner GC sheets compared to the two-step heat treatment followed by the liquid phase exfoliation(LPE)procedure.Nevertheless,the latter method offers a formation of clean samples with a porous or holey feature which has potential for advanced energy-storage applications.

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.

Straightforward synthesis of beta zeolite encapsulated Pt nanoparticles for the transformation of 5-hydroxymethyl furfural into 2,5-furandicarboxylic acid

Encapsulating noble metal nanoparticles(NPs)within the zeolite framework enhances the stability and accessibility of active sites;however,direct synthesis remains a challenge because of the easy precipitation of noble metal species under strong alkali crystallization conditions.Herein,beta zeolite-encapsulated Pt NPs(Pt@Beta)were synthesized via a hydrothermal approach involving an unusual acid hydrolysis preaging step.The ligand—(3-mercaptopropyl)trimethoxysilane—and Pt precursor were cohydrolyzed and cocondensed with a silica source in an initially weak acidic environment to prevent colloidal precipitation by enhancing the interaction between the Pt and silica species.Thus,the resultant 0.2%Pt@Beta was highly active in the transformation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid(FDCA)under atmospheric O2 conditions by using water as the solvent while stably evincing a high yield(90%)associated with a large turnover number of 176.The excellent catalysis behavior is attributable to the enhanced stability that inhibits Pt leaching and strengthens the intermediates that accelerate the rate-determining step for the oxidation of 5-formyl-2-furan carboxylic acid into FDCA.

Auto-ignition of biomass synthesis gas in shock tube at elevated temperature and pressure

Ignition delay times of multi-component biomass synthesis gas （bio-syngas） diluted in argon were measured in a shock tube at elevated pressure （5, 10and 15 bar, 1 bar = 105 Pa）, wide temperature ranges （1,100-1,700 K） and various equivalence ratios （0.5, 1.0, 2.0）. Additionally, the effects of the variations of main constituents （H2：CO = 0.125-8） on ignition delays were investigated. The experimental results indicated that the ignition delay decreases as the pressure increases above certain temperature （around 1,200 K） and vice versa. The ignition delays were also found to rise as CO concentration increases, which is in good agreement with the literature. In addition, the ignition delays of bio-syngas were found increasing as the equivalence ratio rises. This behavior was primarily discussed in present work. Experimental results were also compared with numerical predictions of multiple chemical kinetic mechanisms and Li＇s mechanism was found having the best accuracy. The logarithmic ignition delays were found nonlinearly decrease with the H2 concentration under various conditions, and the effects of temperature, equivalence ratio and H2 concentration on the ignition delays are all remarkable. However, the effect of pressure is rela- tively smaller under current conditions. Sensitivity analysis and reaction pathway analysis of methane showed that R1 （H ＋O2= O -9 OH） is the most sensitive reaction promot- ing ignition and R13 （H ＋O2 （＋M） = HO2 （＋M））, R53（CH3＋H （＋M）= CH4 （＋M））, R54 （CH4＋H= CH3 ＋ H2） as well as R56 （CH4 ＋ OH = CH3 ＋ H2O） are key reactions prohibiting ignition under current experimental conditions. Among them, R53 （CH3 ＋ H （＋M） = CH4 （＋M））, R54 （CH4 ＋ H = CH3 ＋ H2） have the largest posi- tive sensitivities and the high contribution rate in rich mixture. The rate of production （ROP） of OH of R1 showed that OH ROP of R1 decreases sharply as the mixture turns rich. Therefore, the ignition delays become longer as the equiva- lence ratio increases.

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.

Mathematical Simulation and Design of Three-Phase Bubble Column Reactor for Direct Synthesis of Dimethyl Ether from Syngas

A three-phase reactor mathematical model was set up to simulate and design a three-phase bubble column reactor for direct synthesis of dimethyl ether （DME） from syngas, considering both the influence of part inert carrier backmixing on transfer and the influence of catalyst grain sedimentation on reaction. On the basis of this model, the influences of the size and reaction conditions of a 100000 t/a DME reactor on capacity were investigated. The optimized size of the 10000 t/a DME synthesis reactor was proposed as follows： diameter 3.2 m, height 20 m, built-in 400 tube heat exchanger （Ф 38×2 mm）, and inert heat carrier paraffin oil 68 t and catalyst 34.46 t. Reaction temperature and pressure were important factors influencing the reaction conversion for different size reactors. Under the condition of uniform catalyst concentration distribution, higher pressure and temperature were proposed to achieve a higher production capacity of DME. The best ratio of fresh syngas for DME synthesis was 2.04.

Molybdenum carbide as catalyst in biomass derivatives conversion

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)footprint.As a practice pathway,it is of significance to produce biofuel and platform chemicals from sustainable biomass resources.However,the research and development of high-efficiency catalysts remain one key scientific challenge.Among the catalysts developed,transition metal carbides,especially molybdenum carbide,show promising performances on biomass-based conversion.Significant 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,etc.The 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 modulation.The 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 highlighted.In addition,the possible deactivation mechanisms of molybdenum carbide are also presented in the review.This review provides systematic and fundamental information for the further design and development of molybdenum carbide for the conversion of biomass resources.

Latest advances in ionic liquids promoted synthesis and application of advanced biomass materials

The utilization of sustainable resources provides a path to relieving the problem of dependence on fossil resources. In this context, biomass materials have become a feasible substitute for petroleum-based materials. The development of biomass materials is booming and advanced biomass materials with various functional properties are used in many fields including medicine, electrochemistry, and environmental science. In recent years, ionic liquids have been widely used in biomass pretreatments and processing owing to their “green” characteristics and adjustable physicochemical properties. Thus, the effects of ionic liquids in biomass materials generation require further study. This review summarizes the multiple roles of ionic liquids in promoting the synthesis and application of advanced biomass materials as solvents, structural components, and modifiers. Finally, a prospective approach is proposed for producing additional higher-quality possibilities between ionic liquids and advanced biomass materials.

Biomass-derived carbon dots with pharmacological activity for biomedicine:Recent advances and future perspectives

Carbon dots(CDs),a type of nanoparticle with excellent optical properties,good biocompatibility,and small size,are finding increasing application across the fields of biology and biomedicine.In recent years,biomass-derived CDs with pharmacological activity(BP-CDs)derived from herbal medicines(HMs),HMs extracts and other natural products with demonstrated pharmaceutical activity have attracted particular attention.Herein,we review recent advances in the development of BP-CDs,covering the selection of biomass precursors,different methods used for the synthesis of BP-CDs from natural sources,and the purification of BP-CDs.Additionally,we summarize the many remarkable properties of BP-CDs including optical properties,biocompatibility and pharmaceutical efficacy.Moreover,the antibacterial,antiviral,anticancer,biosensing,bioimaging,and other applications of BP-CDs are reviewed.Thereafter,we discuss the advantages and disadvantages of BP-CDs and Western drug-derived CDs,highlighting the excellent performance of BP-CDs.Finally,based on the current state of research on BP-CDs,we suggest several aspects of BP-CDs that urgently need to be addressed and identify directions that should be pursued in the future.This comprehensive review on BP-CDs is expected to guide the precise design,preparation,and future development of BP-CDs,thereby advancing the application of BP-CDs in biomedicine.

Green and large-scale production of ammonia:Laser-driven pyrolysis of nitrogen-enriched biomass

As a vital chemical,ammonia(NH3)plays an irreplaceable role in many fields such as chemical synthesis and energy storage.Green renewable biomass can be converted into biofuels,but its nitrogen resources are underused throughout.Laser-driven pyrolysis is envisaged to debuts as a bridge to connect them to realize the direct conversion from nitrogen-rich biomass into ammonia.The pulsed laser-induced local-transient thermal effect recognized the biological nitrogen resources conversion,such as cheap and plentiful yeasts,to small gaseous molecules and achieved spectacular ammonia production rate up to 260.4 mg/h,an order of magnitude higher performance than thermochemical ammonia synthesis.Simultaneously,the tiny hot point generated by a low-energy laser(20W)guarantees the whole ammonia synthesis reaction systemis in amild environment of low temperature and normal pressure.Additionally,the remaining solid residue after laser-driven pyrolysis also can be further exploited as a highly active catalyst for electrocatalytic nitrate reduction reaction(NIRR).

Advancements in transition bimetal catalysts for electrochemical 5-hydroxymethylfurfural(HMF) oxidation

The electrochemical oxidation of 5-hydroxymethylfurfural(HMF) represents a significant avenue for sustainable chemical synthesis, owing to its potential to generate high-value derivatives from biomass feedstocks. Transition metal catalysts offer a cost-effective alternative to precious metals for catalyzing HMF oxidation, with transition bimetallic catalysts emerging as particularly promising candidates. In this review, we delve into the intricate reaction pathways and electrochemical mechanisms underlying HMF oxidation, emphasizing the pivotal role of transition bimetallic catalysts in enhancing catalytic efficiency. Subsequently, various types of transition bimetallic catalysts are explored, detailing their synthesis methods and structural modulation strategies. By elucidating the mechanisms behind catalyst modification and performance enhancement, this review sets the stage for upcoming advancements in the field, ultimately advancing the electrochemical HMF conversion and facilitating the transition towards sustainable chemical production.

Mechanism and catalytic performance for direct dimethyl ether synthesis by CO2 hydrogenation over CuZnZr/ferrierite hybrid catalyst

Direct synthesis of dimethyl ether(DME)by CO2 hydrogenation has been investigated over three hybrid catalysts prepared by different methods:co-precipitation,sol-gel,and solid grinding to produce mixed Cu,ZnO,ZrO2 catalysts that were physically mixed with a commercial ferrierite(FER)zeolite.The catalysts were characterized by N2 physisorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),temperature programmed desorption of CO2(CO2-TPD),temperature programmed desorption of NH3(NH3-TPD),and temperature programmed H2 reduction(H2-TPR).The results demonstrate that smaller CuO and Cu crystallite sizes resulting in better dispersion of the active phases,higher surface area,and lower reduction temperature are all favorable for catalytic activity.The reaction mechanism has been studied using in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS).Methanol appears to be formed via the bidentate-formate(b-HCOO)species undergoing stepwise hydrogenation,while DME formation occurs from methanol dehydration and reaction of two surface methoxy groups.

生物质碳点的合成及应用进展

从生物质衍生碳点(BCDs)的制备和BCDs在传感器、生物医学、电气应用、食品检测等领域的应用,对国内外BCDs的研究进展进行了综述,并对其未来发展进行展望。

One-pot cascade conversion of xylose to furfuryl alcohol over a bifunctional Cu/SBA-15-SO3H catalyst

The conversion of hemicellulose-derived xylose to furfuryl alcohol is a practical procedure for producing value-added chemicals from biomass.In this study,a bifunctional Cu/SBA-15-SO3 H catalyst was employed for the one-pot catalytic conversion of xylose to furfuryl alcohol with a yield of up to 62.6% at the optimized conditions of 140℃,4 MPa,and for 6 h in a biphasic water/n-butanol solvent.A high reaction temperature resulted in further hydrogenation to 2-methyl furan,while a high hydrogen pressure led to a side hydrogenation reaction to xylitol.The biphasic solvent allowed xylose solvation as well as furfuryl product extraction.The acidic-SO3 H sites and Cu sites co-existed,maintained a balance,and cooperatively catalyzed the cascade conversion.Excessive acidic sites and large pores could promote the xylose conversion,although a low furfuryl alcohol yield was obtained.This catalytic system could be potentially applied to the one-pot synthesis of furfuryl alcohol from hemicellulose-derived xylose.

生物质合成燃料二甲醚的技术

介绍和分析了生物质合成气的制备工艺和合成气组分调整工艺 ,提出了生物质合成液体燃料二甲醚的工艺路线 。

生物质间接液化一步法合成燃料二甲醚

结合合成气制备液体燃料二甲醚的技术特点 ,对生物质在不同气化介质中的气化工艺以及气体组分分布进行了分析 ,对生物质合成气的自有特点和组分调整等重要制备过程进行了分析探讨 ,参考煤气化制备二甲醚的工艺过程 ,提出了生物质间接液化一步法合成液体燃料二甲醚的工艺路线设想 .