Fabrication of a sinter-resistant Fe-MFI zeolite dragonfruit-like catalyst for syngas to aromatics conversion

Direct conversion of syngas to aromatics has great potential to decrease fossil fuel dependence.Here,a unique structured hybrid catalyst composed of Fe_(3)O_(4) nanoparticles intimately dispersed inside an acidic zeolite is developed.1 to 4 nm sized Fe_(3)O_(4) nanoparticles end up evenly dispersed in an acidic and slightly mesoporous Al-ZSM-5 based on Fe_(3)O_(4) restructuring during co-hydro thermal synthesis using organosilane modification.A very high aromatic productivity of 214 mmolaromatics h^(-1) gFe^(-1) can be obtained with a remarkable 62%aromatic selectivity in hydrocarbons.This catalyst has excellent sintering resistance ability and maintains stable aromatics production over 570 h.The synthetic insights that postulate a mechanism for the metastable oxide-zeolite reorganization during hydrothermal synthesis could serve as a generic route to sinter-resistant oxide-zeolite composite materials with uniform,well-dispersed oxide nanoparticles in close intimacy with-and partially confined in-a zeolite matrix.

In situ synthesis of biomass-derived Ni/C catalyst by self-reduction for the hydrogenation of levulinic acid to γ-valerolactone

Herein,we reported in situ synthesis of biomass-derived Ni/C catalyst by self-reduction with pomelo peel.Compared with the conventional method, which includes carbonization, activation, impregnation and reduction, the entire preparation process was simplified to two steps, which was more straightforward. This synthesis method was green as Ni/C can be prepared without any additional chemical and the self-reduction process was realized in N2, which can avoid using H2 thus averting some problems such as storage, transportation and safety of H2. Meanwhile, the size and dispersion of Ni particles can be controlled by changing carbonization temperature.The synthesis mechanism of Ni/C catalyst with selfreduction was investigated, which was mainly attributed to the carbon and reducing gas produced during the carbonization process.For the catalytic performance of GVL synthesis, a high yield (94.5%) can be obtained and it exhibited good stability up to 5 cycles without obvious loss of catalytic activity.

Understanding the geometric and electronic factors of PtNi bimetallic surfaces for efficient and selective catalytic hydrogenation of biomass-derived oxygenates

Ni-base catalysts are promising candidate for the hydrogenation of furfural(FAL) to high-value chemicals.However,slow intermediate desorption and low selectivity limit its implementation.Identifying the catalytic performance of each active sites is vital to design hydrogenation catalyst,and tuning the geometrical sites at molecule level in PtNi could lead to the modification of electronic structure,and thus the selectity for the hydrogenation of FAL was modulated.Herein,PtNi hollow nanoframes(PtNi HNFs) with three dimensional(3 D) molecular accessibility were synthesized,EDX results suggested that Ni was evenly distributed inside of the hollow nanoframes,whereas Pt was relatively concentrated at the edges.DFT calculation demonstrated that PtNi significant decrease the desorption energy of the intermediates.This strategy could not only enhance the desorption of intermediates to improve the catalytic performance,but also transfer the adsorption mode of FAL on catalyst surface to selective hydrogenation of FAL to FOL or THFA.The PtNi HNFs catalyst afforded excellent catalytic performance for selective hydrogenation of a broad range of biomass-derived platform chemicals under mild conditions,especially of FAL to furfuryl alcohol(FOL),in quantitative FOL yields(99%) with a high TOF of 2.56 h^(-1).It is found that the superior performance of PtNi HNFs is attributed to its 3 D hierarchical structure and synergistic electronic effects between Pt and Ni.Besides,the kinetic study demonstrated that the activation energy for hydrogenation of FAL was as low as 54.95 kJ mol^(-1).

Synthesis of high density and low freezing point jet fuels range cycloalkanes with cyclopentanone and lignin-derived vanillins

In this work,a“cyclopentanone-vanillin”strategy was proposed for the preparation of jet fuel range cycloalkanes from lignocellulose-derived ketones and lignin-derived aldehydes via aldol condensation and hydrodeoxygenation(HDO).Ethanolamine lactate ionic liquid(LAIL)exhibited excellent catalytic activity in the aldol condensation of cyclopentanone and vanillin.Desired mono-condensation and bicondensation products were obtained with yield of 95.2%at 100℃.It is found that the synergy effects between amino group of ethanolamine and hydroxyl group of lactic acid play a key role in the aldol condensation.The condensation products were converted into cycloalkanes by HDO over 5%Pd/Nb_(2)O_(5)catalyst.The density of the obtained HDO products is 0.89 g/cm^(3)and the freezing point is lower than-60℃.These results suggest that the resulted cycloalkanes can be used as additives to improve the density and low-temperature fluidity of the jet fuels.

Facile synthesis of hydrochar-supported catalysts from glucose and its catalytic activity towards the production of functional amines

Since the utilization of abundant biomass to develop advanced materials has become an utmost priority in recent years,we developed two sustainable routes(i.e.,the impregnation method and the one-pot synthesis)to prepare the hydrochar-supported catalysts and tested its catalytic performance on the reductive amination.Several techniques,such as TEM,XRD and XPS,were adopted to characterize the structural and catalytic features of samples.Results indicated that the impregnation method favors the formation of outer-sphere surface complexes with porous structure as well as well-distributed metallic nanoparticles,while the one-pot synthesis tends to form the inner-sphere surface complexes with relatively smooth appearance and amorphous metals.This difference explains the better activity of catalysts prepared by the impregnation method which can selectively convert benzaldehyde to benzylamine with an excellent yield of 93.7%under the optimal reaction conditions;in contrast,the catalyst prepared by the one-pot synthesis only exhibits a low selectivity near to zero.Furthermore,the gram-scale test catalyzed by the same catalysts exhibits a similar yield of benzylamine in comparison to its smaller scale,which is comparable to the previously reported heterogeneous noble-based catalysts.More surprisingly,the prepared catalysts can be expediently recycled by a magnetic bar and remain the satisfying catalytic activity after reusing up to five times.In conclusion,these developed catalysts enable the synthesis of functional amines with excellent selectivity and carbon balance,proving cost-effective and sustainable access to the wide application of reductive amination.

Efficient production of ethyl levulinate from cassava over Al2(SO4)3 catalyst in ethanol–water system

One-pot achievement of ethyl levulinate from cassava was conducted in ethanol-water system over several simple sulfate salt catalysts.Al_2(SO_4)_3 catalyst had the best performance in synthesizing ethyl levulinate comparing with those of a series of sulfate salts.The highest yields of ethyl levulinate was up to39.27%as well as 7.78%levulinate acid when cassava was catalyzed in ethanol medium by adding 10 wt%water.^(13)C and ~1H NMR spectroscopic investigations confirmed that isomerization of glucose to fructose over Al_2(SO_4)_3 catalyst is an important step in producing ethyl levulinate and levulinate acid.Due to aggregations of Al^(3+) under hydrothermal conditions,tiny amount of Al^(3+) were detected in filtrate at the percentage of 0.32%even if in absolute water.Bronsted and Lewis acids could improve the yield of ethyl levulinate and levulinate acid by synergistic effect.All results suggested that A1_2(SO_4)_3 was a simple and efficient catalyst for ethyl levulinate and levulinate acid production.

Selective hydrogenolysis of 5-hydroxymethylfurfural to 2,5-dimethylfuran over Co_3O_4 catalyst by controlled reduction

2,5-dimethyfuran(DMF), which is produced from 5-hydroxymethyfurfural(HMF) by hydrodeoxygenation(HDO), is a high quality fuel due to the high heating value, the high octane number and the suitable boiling point. Selective hydrogenation of HMF into liquid fuel DMF has been widely researched. In this paper, Co_3O_4 catalyst was prepared by co-precipitation and was reduced at different temperatures to form Co–CoO_x catalysts. The characterization of catalysts was tested by XRD, TEM, XPS, TPR, BET and NH3-TPD.Co–CoO_x possessed a high amount of Co metal and CoO_x acidic sites, wherein Co worked as the active hydrogenation sites and CoO_x acted as the acid promoter to facilitate the selective HDO of HMF to DMF.The synergistic effect of Co–CoO_x is the key for HDO of HMF, obtaining 83.3% of DMF yield at 170 °C, 12 h and the reduction temperature of 400 °C. This method not only saves the catalyst cost, but also promotes the utilization of biomass energy.

Hydrogenolysis of organosolv hydrolyzed lignin over high-dispersion Ni/Al-SBA-15 catalysts for phenolic monomers

Efficiency and recycling of catalysts are important for the lignin hydrogenolysis to obtain phenolic monomers.In this work,a series of highdispersion Ni/AlSBA15 catalysts were prepared by a direct and effective preparation method,and then used in the hydrogenolysis of diphenyl ether(DE)and organosolv hydrolyzed lignin(OHL)for phenolic monomers.The universality of asmade catalysts in different solvents and cyclic performance were investigated.Results showed that the addition of ethylene glycol(EG)during the loading process of Ni promoted the dispersion of metal efficiently.High dispersion of Ni species could highly enhance the conversion of DE and the OHL which Ni/AlSBA15(1EG)exhibited the excellent catalytic performance.Decalin was found to be most effective solvent on the conversion of DE(99.16%).84.77%liquefaction ratio and 21.36%monomer yield were achieved,and no obvious char was observed after the depolymerization of OHL in ethanol solvent at 280℃for 4 h over the Ni/AlSBA15(1EG)catalyst.

Numerical research on biomass wastewater treatment using doublepartition vessel with off-centered impellers

Limited by single function,it is difficult for the traditional stirred vessels to meet the requirements of mixing system in biomass wastewater treatment processes.The estimation of biomass wastewater stirring reactor performance by computational fluid dynamics(CFD)during multiphase reactions is important,due to the uncertainty in the numerical results.In this study,a novel double-partition stirred vessel with eccentrically located impellers was developed for the special subject.In addition,many simulations were carried out with the wastewater from biomass ethanol production as the medium to ensure the high reactor performance.The fluid flow was simulated and analyzed using the turbulent RNG k-ε model and multi reference frames.A good agreement is found between the simulation results and the confirmatory experiment.Moreover,the weir crest and interconnected pore were specially designed for the establishment of the circulation of fluid to maintain different technological conditions in the two regions.The distributions of radial velocities and tangential velocities were concentrated near the stirring blade.From the velocity profile,it is deduced that the flow pattern in the stirred vessel is insensitive to Reynolds number.Finally,this simulation study could contribute to the improvement and optimization of the structure,as well as the operation of the novel stirred vessel.

Application of different molecular sieves in photothermal catalysis of Jatropha oil

The preparation of green and economical bio-aviation fuel is a priority for the sustainable development industry.In this study,Jatropha oil was used as a raw material to catalyze the conversion of raw material to aviation kerosene fraction by photothermal coupling under the conditions of light and low temperature.The correlations among conversion rate,target alkane selectivity,composition distribution,and catalyst microstructure were investigated by X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),nitrogen(N2)adsorption and desorption,X-ray fluorescence(XRF),ammoniatemperature programmed desorption(NH3-TPD),ultraviolet-visible spectrophotometry(UV-Vis),and other characterization.The correlation between conversion and target alkane selectivity and composition distribution and catalyst microstructure was investigated,and different modification methods and different molecular sieve materials were selected.The results showed that the molecular sieves modified with the solid dispersion method could retain the structural stability of titanium dioxide(TiO2)and molecular sieves to a great extent while slightly enhancing the pore capacity and pore size of the catalyst to make it easier to adsorb reactants;the introduction of active metal platinum(Pt)could reduce the forbidden bandwidth of the catalyst,increase the weak acid amount of the catalyst,improve the adsorption capacity of hydrogen(H2),and thus improve the catalytic ability,resulting in a suitable catalyst for this study:P-21.The photothermal catalytic reaction of Jatropha oil using P-21 catalyst obtained 97.21%conversion and 74.99%selectivity of the target alkanes under the optimal process parameters.The results of this study provide effective catalyst parameters for research in the field of clean energy.

Modeling and simulation of biomass air-steam gasification in a fluidized bed

By considering the features of fluidized-bed reactors and the kinetic mechanism of biomass gasification,a steady-state,isothermal,one-dimensional and twophase mathematical model of biomass gasification kinetics in bubbling fluidized beds was developed.The model assumes the existence of two phases–a bubble and an emulsion phase–with chemical reactions occurring in both phases.The axial gas dispersion in the two phases is accounted for and the pyrolysis of biomass is taken to be instantaneous.The char and gas species CO,CO_(2),H_(2),H_(2)O,CH_(4) and 8 chemical reactions are included in the model.The mathematical model belongs to a typical boundary value problem of ordinary differential equations and its solution is obtained by a Matlab program.Utilizing wood powder as the feedstock,the calculated data show satisfactory agreement with experimental results and proves the effectiveness and reliability of the model.

Tandem synthesis of tertiary amines using graphene encapsulated Ni nocatalyst via nitro compounds hydrogenation and primary amine methylation

Development of the economic, environmentally friendly synthesis of amines from nitro compounds remains important and challenging. In this work, the graphene shell encapsulated none noble Ni-based catalysts were successfully designed and synthesized via an environmentally friendly method using H2O or Et OH as solvent. These fresh and recycling catalysts were characterized by X-ray diffraction and X-ray photoelectron spectroscopy. For the nitro compounds hydrogenation, Ni@C-600-H2O exhibits the best catalytic activity to achieve 100 mol/mol conversions of nitrobenzene and 99% selectivity of aniline under mild reaction conditions of 1.0 MPa H2and 60°C.Many halogen-substituted, olefin substituted nitro compounds and aliphatic nitro compounds were investigated and desired products were obtained in excellent selectivity. What is more, the catalyst had excellent stability and could be recycled 13 times without any significant loss in selectivity and activity. Furthermore, we also reported the methodology for tertiary amines synthesis using Ni-based catalyst via one-pot, cost-effective tandem combination reaction with nitrobenzene hydrogenation and amines N-methylation.

One-pot synthesis of Fe_(x)O_(y)nanoparticles embedded within N-doped carbon layers as highly efficient and selective catalysts for the hydrogenation of nitroarenes

Inhibiting the side reactions while promoting hydrogenation are the main target for the production of functional anilines from nitroarenes;consequently,the preparation of an ideal catalyst to improve chemical selectivity is one of the hot issues.In this work,we provided an easy-to-prepare catalyst with Ndoped carbon layers,where the Fe_(x)O_(y)nanoparticles were encapsulated and distributed uniformly.The structural features of catalyst were characterized by several techniques,and the selected catalyst was next applied to the hydrogenation of nitrobenzene under varied conditions,involving temperature,holding period and H2 pressure.Subsequently,we conducted the synthesis of more than 16 substrates for the corresponding anilines with varied functional groups.The hydrogenation protocol to gram-scale synthesis as well as lifecycle performance were also demonstrated in the batch reactor,together with the explanation of its catalytic mechanisms.Overall,the present work provides an available preparation of simple but highly efficient catalysts for the production or aromatic amines,which will be benefit for the sustainable development of this field in near future.

Facile synthesis of N-doped graphene encapsulated Ni@N/C catalyst and its catalysis for highly selective semi-hydrogenation of alkynes

Although precious transition metals such as palladium,platinum,and iridium are widely used in hydrogenation reactions,the earth-abundant transition metal-catalyzed highly selective semi-hydrogenation of terminal alkynes to terminal alkenes remains poorly developed and a challenge.Herein we demonstrate the excellent selective,cost-effective semi-hydrogenation of terminal alkynes via a novel graphene encapsulated Ni@N/C catalyst.The graphene layer encapsulated nano-catalyst Ni@N/C could significantly avoid metal leaching and improve the stability of the catalyst.The strong interaction of nitrogen with the Ni nanoparticles regulates the activity of Ni towards selective semi-hydrogenation of terminal alkynes.Substrates having un-functionalized as well as functionalized substituents,and substrates having sensitive functional groups(olefins,ketones)which pose a challenge to hydrogenate,were semi-hydrogenated with excellent conversion(up to 99%)and selectivity(up to 99%)under optimized reaction conditions.