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In the context of the preparation of liquid fuels derived from biomass with zero COfootprint, fatty acids appear as suitable feedstocks. However, reduction of carboxylic acid groups usually requires harsh reaction conditions and the development of efficient solid catalysts. Herein, bimetallic Ni-Mo nitrides have been obtained by a procedure not involving nitridation of the corresponding oxide, but reductive decomposition of the tris(ethylenediamine)nickel molybdate at temperatures between 550 and 700 °C. Successful formation of the NiMoN nitride is confirmed by X-ray diffraction. NiMoN samples are found to be efficient catalysts for the hydrodeoxygenation of palmitic acid to C/Calkanes with a combined selectivity over 90 and 100% palmitic acid conversion and higher activity than analogous Ni-Mo nitrides obtained by NHnitridation of NiMoO. NiMoN is found recyclable with only a slight decay in the catalytic activity upon consecutive reuses attributable to the neutralization of acid sites. The present results show an opportunity that bimetallic nitrides offer as robust advanced solid catalysts for reactions of biomass conversion requiring harsh conditions., This work was financially supported by National Natural Science Foundation of China (no. 21972099), the Application Foundation Program of Sichuan Province (no. 2021YJ0305), and 111 project (no. B17030). Financial support by the Spanish Ministry of Science and Innovation (Severo Ochoa and RTI2018-89237-CO2-R1) and Generalitat Valenciana is gratefully acknowledged. We thank Yunfei Tian of the Analytical & Testing Center of Sichuan University for XPS experiments. X.D. is also grateful for financial support from China Scholarship Council (CSC).

Ru/SBA-15 showed excellent activity for phenol to cyclohexanol at 20 °C and exhibited a zero-order character with low Ea of 10.88 kJ mol−1. A high yield of 37.4% of cyclohexanol was obtained at 80 °C and 4 h when using eugenol as substrate.

International audience; A series of nickel-cerium-promoted mesoporous silica (SBA-15) catalysts modified with different loadings of yttrium were synthesized by cetyltrimethylammonium bromide (CTAB)-assisted impregnation. The catalysts were tested in CO2 methanation reaction and characterized by N2 sorption, X-ray fluorescence (XRF), small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (XRD), H2 chemisorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), CO2 temperature-programmed desorption (CO2-TPD), and thermogravimetric analysis coupled with mass spectrometry (TGA-MS). The best catalytic performance in CO2 methanation was found for Y-modified NiCe/SBA-15 catalysts compared to the unpromoted sample. The modification with 10 wt% of yttrium gave the highest CO2 conversion of 61% ± 2% at 350 °C. We attribute this increase to an improved dispersion of Ni, increased reducibility of Ni species, higher ratio of Ce3+/(Ce3+ + Ce4+), and increased moderate basicity found for 15Ni10Ce10Y/SBA-15. This paper shows that 10 wt% of Y loading not only improves the catalytic activity in CO2 methanation, but also gives stable performance. The tested 15Ni10Ce10Y/SBA-15 catalyst did not exhibit activity loss during 26 h of time-on-stream (TOS) experiment at 350 °C. Moreover, carbon deposits and sintered nickel particles could hardly be found in 15Ni10Ce10Y/SBA-15 catalyst used for 7 h.

Tetra-ortho-substituted, heteroaryl and cyclic azobenzenes have emerged as three key strategies on morphology design of photoswitch to diversify controllability. Cyclic azobenzene is of particular utilization in photo-energy conversion due to rigid and ring-strain structure. Despite the well-recognized diazocine, the photo-switching properties of seven-membered cyclic azobenzenes (diazepines) have yet been exploited. Herein, we report a family of dibenzo[b,f][1,4,5]chalcogenadiazepines (DBChDs) and their T-type photo-switching nature with tunable relaxation rate. Based on experiments together with DFT calculations, we found that an unsymmetric 2-bithiophenyl-dibenzo[b,f][1,4,5]thiadiazepine exhibited an efficient response to 445 nm laser stimulation (quantum efficiency, Φ

Though nickel phosphides had been used widely to transform biomass into bio-fuel, the impact of support on the crystal formation was not clear. Herein, nickel and phosphides loaded on SiO2, ZSM-5 and γ-Al2O3 were synthesized and the interaction between Ni/P and the supports was studied. Pure Ni12P5 and pure Ni formed on SiO2 and γ-Al2O3, respectively, whereas the mixture of Ni12P5 and Ni formed on ZSM-5. The formation of AlPO4 species was the main factor for the absence of Ni12P5 on Ni/γ-Al2O3 catalyst. Furthermore, the support also had a significant impact on the active phase with different particle size and dispersion, and further affected the performance. The highest fuel yield of 67.3 wt.% was obtained on Ni12P5/SiO2 catalyst, which might be attributed to the appropriate acid sites and proper Ni12P5 size. In addition, the catalysts with Ni12P5 crystal phase displayed good resistance to coke deposition. The findings are important for clarification of the role of support in nickel phosphide active phase formation and coke deposition.

The huge demand of lactic acid in widespread applications has significantly impelled the development of cost-effective strategy for the production of lactic acid, in particular its derivative (methyl lactate, MLA) due to the simpler separation and purification process. Herein, in this work, we developed a series of robust but simple In/γ-Al2O3 catalysts with different In loadings. The results indicated that In doping obviously increased the amount of mid-strong acid on the catalyst, which significantly facilitated the selective cleavage of C3-C4 bond in C6 sugar (rate-controlling step), as well as the next esterification reaction. 12-In/γ-Al2O3 catalyst, with the most mid-strong acid sites, exhibited the best catalytic activity for MLA production from renewable sugars in methanol solvent. The addition of only a small amount of water could accelerate sugar dissolution in methanol solvent, and alkali (K2CO3) addition further promoted C3-C4 cleavage, thus yielding more C3 intermediates. When dihydroxyacetone and pyruvaldehyde intermediates were employed as feedstock, as high as 86.0 % and 98.0 % yields of MLA could be obtained, respectively. Even in the case of glucose and fructose as feedstock, MLA yields were up to 49.0 % and 54.2 %, respectively, under the optimized conditions. This work might provide a potential approach for the synthesis of lactic acid and its derivatives with low production cost.

Metal salt soaking–torrefaction conversion technology was investigated. It was found that AlCl3 pretreatment of pubescens favored observably the yield of liquid and small-molecular products in torrefaction via changing the composition and structure of the raw material. The maximum conversion of pretreated samples, washed (PSW) and Yliquid were 15.5 and 10.8 wt % (with 0.26 wt % monosaccharides, 0.26 wt % carboxylic acids, 0.38 wt % furan compounds, and 1.28 wt % phenols), where 20.4 wt % hemicellulose, 22.9 wt % cellulose, and 5.7 wt % lignin were converted, respectively. However, for pretreated samples (PS), the maximum conversion and Yliquid reached 44.2 and 32.1 wt %, respectively, along with 96.0 wt % hemicellulose and 31.8 wt % cellulose converted, yielding 2.39 wt % monosaccharides, 5.14 wt % carboxylic acids, 2.60 wt % furan compounds and 10.52 wt % phenols, indicating obvious catalytic effects of residual AlCl3 on the decomposition of the three major components in torrefaction. Two-dimensional HSQC and electrospray ionization mass spectrometry (ESI-MS) characterizations further confirmed the dominant formation of oligomers derived from holocellulose, lignin, and cross-linkage involving the lignin–carbohydrate complex, indicating that the catalytic thermal cleavage of β-O-4, C-O-C, β-β, 5–5, 4-O-5, Cα–Cβ, and α-O-4 linkages by aluminum species in the samples benefited the yield of liquid as well as monophenols.

Silica (SiO 2 ) and iron-incorporated silica (Fe/SiO 2 ) materials are prepared from rice husk pyrolytic residues through alkali treatment, co-precipitation and calcination. The prepared material is characterized by ICP-AES, XRD, FT-IR, UV-vis DRS, XPS, SEM-EDS and TEM, and the results indicate that the prepared materials are mesoporous, where framework and extra-framework iron species concurrently exist in the Fe/SiO 2 . The prepared materials are applied to treat methylene blue (MB) solution, where influencing factors such as temperature, pH, the dosage of H 2 O 2 and Fe/SiO 2 are studied. Under the optimal conditions, Fe/SiO 2 shows a much better adsorption effect than SiO 2 , where Fe/SiO 2 can adsorb 85 % of MB within only 2 min, and almost 98.8 % color is removed within 90 min in the presence of both Fe/SiO 2 and H 2 O 2 . Only 0.46 % iron leaches from Fe/SiO 2 , and it performs relatively good results in the recycle utilization where almost 90 % of chroma is removed within 10 min or 20 min. Hydroxyl radicals are successfully captured by electron paramagnetic resonance (EPR) experiment and it proves that a heterogeneous Fenton-like system form in the presence of both Fe/SiO 2 and H 2 O 2 , i.e., Fe/SiO 2 acts as both adsorbent and catalyst in the treatment process of MB.

The reaction mechanism and enantioselectivity of asymmetric Michael addition reaction between alkynone (R1) with α-angelica lactone (R2) catalyzed by chiral N, N'-dioxide-Sc(III) complex were investigated at the M06/6-31G(d,p) (acetonitrile, SMD) level. The α-angelica lactone substrate could isomerize to the active enolized form in the presence of Sc(OTf)3 reagent, assisted by the counter trifluoromethanesulfonate anion OTf-. The alkynone substrate and enolized angelica lactone (or its anion) coordinated to Sc(III) center of N,N'-dioxide-Sc(III) complex catalyst simultaneously, forming a high active hexacoordinate-Sc(III) complex. The catalytic reaction occurred via a two-step mechanism, in which C2 Cγ bond formation was predicted to be the chirality-controlling step as well as the rate-determining step (RDS), affording predominant S-enantiomer. The counterion OTf- facilitated C H construction as a proton-shuttle, producing mainly E-configuration product observed in experiment. The steric repulsion from the ortho-substituent of amide moiety as well as the chiral backbone of N, N'-dioxide-Sc(III) catalyst played the key role for chiral induction in the asymmetric reaction. The less destabilizing Pauli repulsion and more stabilizing attractive interaction, especially the orbital interaction, along the si-face attack pathway enhanced the enantiodifference of the two competing pathways for high enantioselectivity. The energy barriers for E/Z isomerization of S or R-enantiomer assisted by HOTf was as high as 34.6–35.0 kcal mol−1, indicating that the product with Z-conformation was difficult to be obtained. These results were in good agreement with experimental observations.

Efficient depolymerization of lignocellulosic biomass is a prerequisite for sugar production and its subsequent upgradation to fuels and chemicals. Organic carbonate solvents, i.e., propylene carbonate (PC), ethylene carbonate (EC), and dimethyl carbonate (DMC), which are low in toxicity and biodegradable, were investigated as "green"co-solvents (PC/H2O, EC/H2O, DMC/H2O, solvent ratio 1:1) for depolymerization of cellulosic paper towel waste. PC/H2O and EC/H2O enhanced the depolymerization of paper towel waste and improved the total sugar yield (up to ∼25 C mol %) compared to H2O only (up to ∼11 C mol %) under mild reaction conditions (130 °C, 20 min). The higher performance of PC/H2O and EC/H2O can be attributed to higher availability of reactive protons in the catalytic system that facilitates efficient acid hydrolysis of recalcitrant cellulosic fibers. Moreover, a substantial buildup of in-vessel pressure by CO2 release during the microwave-assisted reaction because of decomposition of PC or EC might have accelerated the conversion of paper towel wastes. PC and EC are prospective solvents for lignocellulosic biomass conversion considering their green features and notable catalytic performance, which have a good potential for substituting conventional organic solvents such as dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) that are often considered hazardous in terms of health, safety, and environmental implications.

Ni–Fe catalysts supported on γ-Al2O3 and HZSM-5 were proved to be active for fatty acids conversion into hydrocarbon fuel. The strong interaction between Ni and γ-Al2O3 produced NiAl2O4 species wit...

A series of Ni-Zr catalysts with different Ni loadings were prepared by a novel one-step urea hydrolysis method, and compared to 10Ni/ZrO2 catalyst prepared by ethanol impregnation method. The cata...

The high-efficiency conversion of fructose to 5-hydroxymethylfurfural (HMF) with approving yields is challenging in biorefinery. In this work, we develop an efficient method of preparing HMF from f...

The integrated conversion of raw lignocellulosic biomass selectively to γ-valerolactone (GVL), using formic acid as the sole hydrogen resource, is of great importance from economic and engineering ...

The production of lactic acid (LaA) directly from actual biomass via a one-step reaction without pretreatment by chemocatalysis has shown high potential for satisfying its enormous demand in widesp...

Valuable furfuryl alcohol (FFA) and 2,5-dihydroxymethylfuran (DHMF) could be produced by selective hydrogenation of biomass-derived furfural (FF) and 5-hydroxymethylfurfural (HMF) with high atom economy. In this study, SBA-15 (a kind of mesoporous silica molecular sieve)-supported low metal loading (3 wt% total metal content) PtNi alloy catalyst (PtNi/SBA-15) was synthesized via two steps, including the generation of PtNi alloy by hydrothermal method, and the immobilization of PtNi alloy on SBA-15. PtNi/SBA-15 has ordered mesoporous structure with high surface area, and high dispersion of the PtNi alloy with the formation of Ptδ−-Niδ+ surface pairs on SBA-15, which benefit hydrogen activation and selective carbonyl hydrogenation. The selective hydrogenation of FF and HMF over PtNi/SBA-15 in water solvent at 303 K with 1.5 MPa H2 within 2 h, could respectively yield 64.6% FFA with 77.0% selectivity, and 68.2% DHMF with 81.9% selectivity. Besides, PtNi/SBA-15 exhibited a satisfactory water resistance and stability after recycling at least five runs.

The production of fuel from the hydrodeoxygenation of vegetable oils has been extensively investigated on account of the decline of petroleum-based fuels and increase of ecological problems. The conversion of jatropha oil over Al-MCM-41-supported Ni, W, and Ni–W catalysts was studied at 3 MPa and 360 °C. Over the monometallic Ni and W catalysts, the biofuel yield was low, about 19.3 and 12.5 wt %, respectively, whereas the highest biofuel yield reached 63.5 wt % over the Ni–W bimetallic catalysts. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high-resolution TEM results suggested that the proper amount of Ni and W would form a Ni17W3 active phase, the particle size of which varied with the content of Ni and W or preparation methods. The crystalline Ni17W3 phase formed when the content of both Ni and W reached 10%. With further increase of the content of W or Ni to 15%, the crystal size of Ni17W3 grew from 7 to 14 nm or to 20 nm, whereas the biofuel yield decreased with the increase of the Ni17W3 crystal size. The 10Ni–10W/Al-MCM-41 catalyst with the Ni17W3 crystal size of 7 nm showed the best performance for the transformation of jatropha oil into high-grade biofuel.

Lactic acid is an attractive target platform chemical obtained from biorefinery processes based on renewable resources. This study focuses on the recovery of lactic acid from corn stover hemicellulose-derived liquor. Two processes were investigated comparatively. In process I, under the optimized conditions of 10 wt % trioctylamine/octanol, the extraction efficiency and distribution coefficient of lactic acid were 50.8% and 1.03, respectively. In process II, a salting-out extraction step was introduced, which had significant impacts on the following reactive extraction process. The extraction efficiency and distribution coefficient of lactic acid were about 32.2% and 3.85 times higher than that of process I, respectively. All residual sugars and most of the salts (82.8%) could be removed by the salting-out extraction system used. Additionally, five extraction cycles with back-extraction and solvent regeneration were performed, and the results showed that the extraction system still exhibited stable performance. Effective extraction of lactic acid from crude reaction liquor of corn stover was realized by first salting-out and consecutive reactive extraction, which provided a potential method for recovery of lactic acid from actual biomass-derived liquor.

Direct hydrothermal conversion (HC) of macroalgae Enteromorpha prolifera was conducted over the temperature range of 140–240 °C. At 160 °C, monosaccharides and small molecular acids began to generate. A high yield (18.8%) of monosaccharides was obtained at 180 °C, whereas 29.6% of small molecular organic acids was attained at 200 °C. Formic acid (FA) was then employed as a catalyst, which could selectively catalyze the conversion of hemicellulose at low temperature (94.1%, 140 °C). Rhamnose (45.2%) based on the mass of carbohydrates in E. prolifera was produced by the catalysis of 0.7 mL of FA (160 °C, 60 min, 1 g of biomass loading). A low ratio of biomass amount to water was beneficial to the solution of water-soluble components of hemicellulose in E. prolifera to get high yields to monosaccharides. HC showed promise to be an applicable and efficient method in the treatment of E. prolifera with high conversion of carbohydrates.

Metal chloride has shown high potential in biomass conversion to valuable chemicals, but the nature of active species and the corresponding performances on each successive reaction step need further elucidation. In this work, SnCl4 was found to exhibit satisfactory catalytic activity, achieving 64.6 mol % yield of levulinic acid from corncob residue. The levulinic acid obtained could be further converted to more valuable ethyl levulinate with 85% yield without any extra catalyst addition. In water medium, the hydrolysis of SnCl4 resulted in the formation of stannic oxide, H+ and Cl–, which showed a synergistic effect and all contributed to levulinic acid production. It was demystified that Cl– promoted cellulose hydrolysis, and the formed H+ as Bronsted acid mainly contributed to cellulose hydrolysis and fructose dehydration, as well as HMF decomposition to levulinic acid. Sn(IV) species facilitated both glucose-to-fructose isomerization and fructose consumption yielding undesirable polymers, but exhibite...

The selective hydrogenation of lignin-derived phenols under mild conditions is still a challenging work. In this study, 2.0 wt% Pd/γ-Al2O3 catalyst was found to show high catalytic performance for the selective hydrogenation of lignin-derived phenols, giving 100% conversion of substrate and 94.9% yield of cyclohexanols under optimized conditions. The excellent catalytic performance of the 2.0 wt% Pd/γ-Al2O3 catalyst could be possibly ascribed to its higher percentage (93.6%) of surface Pd0 species than other catalysts. The turnover number (TON) of substrate was 1363 with apparent activation energy (Ea) of 22.7 and 13.6 kJ mol−1 for the hydrogenation of 4-ethyl phenol to 4-ethyl cyclohexanone and subsequent hydrogenation for C=O bond over Pd/γ-Al2O3, respectively. The lower Ea could possibly explain the excellent catalytic activity for the full hydrogenation of 4-ethyl phenol to 4-ethyl cyclohexanol. Furthermore, this catalyst showed higher selectivity to hydrolysis and hydrogenation than to hydrogenolysis for the conversion of β-O-4, 4-O-5 and α-O-4 linked lignin-derived dimeric compounds with excellent substrate conversion and cyclohexanol product yield, offering great opportunity and potential for upgrading of lignin-derived phenols to well-defined end products.

International audience; Dry reforming of methane was investigated over Ni-Zr catalysts modified by Aluminum and Manganese. The catalysts were characterized by XRD, CO2-TPD, XPS, TGA, and Raman. Among all prepared catalysts, the 5Al-5 Mn (5 wt% Al and 5 wt% Mn) catalyst showed the highest CH4 and CO2 conversion at 700 °C DRM with low carbon deposition. The CO2-TPD results exhibited that the 5Al-5 Mn catalyst had the highest amounts of both total basic sites and medium-strength basic sites, which could promote the adsorption and activation of CO2 molecule during the DRM reaction, and further reduce the carbon deposition. The XRD results suggested that the addition of both Al and Mn led to smaller nickel particle size. Besides, the lower carbon deposition on 5Al-5Mn and 2.5Al-7.5Mn catalyst was derived from a higher content of surface adsorption oxygen species, which was verified by the O 1s results. While the lower number of basic sites, more strong basic sites and larger particle size on 5Mn and 5Al catalysts result in a higher amount of carbon deposition.

The conversion of methane and water to alcohols could not only reduce the greenhouse effect effectively but also improve the utilization value of methane. In the present work, Ni-Cu/MoOx was prepared by co-impregnation method and applied to the activation of methane and water to produce ethanol. It was found that ethanol could be produced selectively mediated by Ni-Cu/MoOx and a yield of 18.5 μmol was obtained at 240 °C, 2.5 MPa. After CH4 cracking at 500 °C, C-O and alkoxy carbon species formed on the surface of Ni-Cu/MoOx, while C-C coupling and the formation of –CH3O species occurred at nearly 350 °C in the cooling process. The reaction of coupled surface species with water produced ethanol, promoted by the synergetic effects of Ni, Cu and Mo active species. The direct conversion of methane to ethanol on Ni-Cu/MoOx provided clues for the production of value-added oxygenates from methane in further study. The present work prepared Ni-Cu/MoOx by co-impregnation method, which could help the reaction of methane and water, producing ethanol selectively at 250 °C, 2.5 MPa. C-O and alkoxy carbon species were detected by XPS and the variation of CH3O- species during the cracking process were observed by MS, which might be responsible for ethanol production.

Nickel phosphides were known to be promising substitute for noble metal used in various catalysts. The traditional method of controlling the growth of nickel phosphide species, including Ni2P, Ni3P, and Ni12P5, was either modulating Ni/P molar ratio or changing support. Here, we report a new method to control the growth of nickel phosphide species by tuning the types of surface oxygenated group types on activated carbon. The pretreatment of activated carbon with HNO3 remarkably increased the content of O C O groups. In the preparation process of activated carbon supported nickel phosphide catalyst, the O C O groups might interact with P to form P O C O groups. The formed P O C O inhibited the reduction of P species at low temperature, and thus inhibited the formation of the nickel phosphides; whereas at 873 K reduction, the formation of pure Ni2P on activated carbon was enhanced. However, the content of -OH groups content increased on activated carbon treated by NH3∙H2O, which might be favorable for the simultaneous formation of Ni2P and Ni12P5 with 1/1 ratio, and the thus formed catalyst displayed excellent catalytic hydrodeoxygenation activity for palmitic acid. Our results demonstrated how simple base and acid pretreatment could be used to tune the interfacial group distribution, hereby providing a strategy to rationally design transition metal phosphide supported catalysts.

Lignocellulosic biomass as a potential alternative to fossil resource for the production of valuable chemicals and fuels has attracted substantial attention, while reducing the recalcitrance of lignocellulosic biomass is still challenging due to the complex and cross-linking structure of biomass. Solvent system plays important roles in the pretreatment of lignocellulose, enabling the transformation of solid biomass to liquid fluid with better mass and heat transfer, as well as in the selective formation of target products. In particular, H2O/tetrahydrofuran (H2O/THF) system has recently been widely applied in lignocellulose valorization, which has been proved to exhibit outstanding efficiency for the conversion of lignocellulose, solubilization of the intermediates and products, and shifting reaction equilibrium, thereby significantly improving the yield and selectivity of target products, as well as the full utilization of lignocellulose. In addition, THF shows low toxicity, and is known as a renewable solvent which can be produced from bio-derived chemicals. Herein, this review concentrates on the advances of H2O/THF system in lignocellulose valorization in recent years. Several aspects relative to the roles of H2O/THF system are discussed as follows: the pretreatment of lignin, conversion of hemicellulose and cellulose components in lignocelluloses, and the promoting formation of valuable chemicals like furfural, 5-hydroxymethyl furfural (HMF), levulinic acid, and so on, as well as the inhibiting role in humins formation. This review might provide useful information for the design of effective solvent system in full utilization of lignocellulosic biomass.

Nickel/cerium–zirconium oxide (Ni/Ce50–Zr50) and manganese promoted Ni/Ce50–Zr50 (Ni–Mn/Ce50-Zr50) catalysts were prepared using an impregnation method and used in the dry reforming of methane. The catalysts were characterized by H2 temperature-programmed reduction, transmission electron microscopy, X-ray photoelectron spectroscopy, CO2 temperature-programmed desorption, X-ray diffraction, in situ diffuse reflectance infrared Fourier transform spectra, and thermogravimetric analysis. A manganese promoter facilitated the formation of the reaction intermediate—CH2OH species at low temperature. A synergistic effect between Ni and Mn species enhanced the adsorption of CO2 on Ni–Mn/Ce50-Zr50. A manganese promoter not only enhanced the catalytic activity but also led to a high H2/CO ratio product. At 600 °C, under atmospheric pressure, with 20 000 h–1 gas hourly space velocity and CH4/CO2/Ar = 1:1:8, on a Ni–Mn/Ce50-Zr50 catalyst, the CH4 conversion (38.7%), CO2 conversion (40.4%), and the H2/CO ratio (0.83) we...

Lignocellulosic biomass is essentially composed of three components, cellulose, hemicellulose and lignin, with a highly complicated physical structure. The complex network provides significant challenges for the effective analysis of the components in actual biomass while attempted isolation of the individual components usually leads to cross contamination and hence the need to detect the contaminating components. A new method has been developed for the semiquantitative analysis of three main components in important large volume types of lignocellulosic biomass (pubescens, softwood and wheat straw) using confocal microscopy in the absence of stains of other additives. Standard titration and thermogravimetric methods have been used to confirm the confocal microscopy results. This breakthrough opens the door to quick and easy methods for measuring both the ratio of the three major components in biomass and the purity of the isolated components.

The activity of a ZrO2-supported nickel catalyst promoted by silica (Ni-Si/ZrO2) in CO2 dry reforming of methane was carried out at 400 and 450 °C. The catalysts were prepared by an impregnation method and characterized by H2-TPR, XRD, TEM, TG-MS, Raman, XPS, and in situ XPS and DRIFTS. It was discovered that Ni-Si/ZrO2 showed higher initial conversion of CH4 (0.50 s–1) and CO2 (0.44 s–1), and stability for low temperature (400 °C) DRM reaction in comparison to an SiO2-supported nickel catalyst promoted by zirconia (Ni-Zr/SiO2) (0.32 s–1 for both CO2 and CH4). The Ni-Si/ZrO2 catalyst featured the formation of active nickel particles with a small size of 6–9 nm and with slightly strong electronic donor ability, stabilization of the initial metal nickel state under the reaction conditions, and the formation of easily removed C1 coke. However, for the 450 °C DRM reaction, the coke that formed on the Ni-Si/ZrO2 catalyst was mainly C2 coke that was difficult to remove, because the CO2 preferred to combine with...

Solvent-thermal conversion of biomass was promising for obtaining value-added chemicals. However, little was known about the interactions between solvents and biomass in the process, which hindered the effective utilization of biomass. The effects of γ-valerolactone (GVL) and H2O on enhancing pubescens degradation via the cleavage of inter- and intramolecular linkages were studied. At 160 °C, H2O selectively promoted the cleavage of the intermolecular linkages by forming hydrogen bonds, making mainly contributions to hemicellulose dissolution, while GVL and H2O promoted lignin dissolution by forming hydrogen bonds with −OCH3 group of lignin. H2O promoted the cleavage of β-(1,4)-glycosidic bonds in hemicellulose derived oligomers to xylose, while the oxygen in the ring of GVL might interact with hydroxyl groups of xylose unit to enhance the dehydration of xylose to furfural, whereas GVL with H2O promoted the depolymerization of lignin to oligomers mainly including β-O-4′ and β–β′ linkages connecting to G a...

Pd/NbOPO4 multifunctional catalyst was prepared and used for catalytic hydrotreatment upgrading of bio-oil, which was obtained from low-temperature torrefaction (LTT) of pubescens and contained mainly lignin oligomers. The upgrading temperatures were investigated at 220–280 °C. Pd/NbOPO4 exhibited good performance for the effective depolymerization of oligomers with increasing temperature. It was revealed that both Bronsted acid sites and Lewis acid sites existed on NbOx, which contributed to the cleavage of the C–O–C bond. Furthermore, esterification, hydrogenation, and O-alkylation of monomeric derivatives also occurred simultaneously during the depolymerization process. After hydrotreatment upgrading, the average molecular weight of bio-oil decreased from Mw = 320 Da (Mn = 298 Da) to Mw = 273 Da (Mn = 254 Da) and the bio-oil quality was improved dramatically. The oxygen content decreased from 29.53 to 9.78 wt %. The upgraded bio-oil obtained at 280 °C had a heating value of 40.48 MJ kg–1, which was muc...

In this study, alumina-supported Ni Mo catalysts were carburized to obtain alumina-supported nickel–molybdenum carbides as potential catalysts for dry reforming of methane. The typical carbide was compared with a low carburized material (in 5% H2/CH4) and a reduced Ni Mo catalyst. It was shown that the passivated alumina-supported Ni Mo catalysts by carbon lead to higher reactivity, selectivity, and stability for dry methane reforming reaction.

The exploration of potential application of glycerol is of particular importance for solving the oversupply of glycerol as an unavoidable byproduct of biodiesel and affording profitable possibilities for sustainable biodiesel. Herein, we developed a simple, cheap but robust Cu1Mg4 catalyst, which exhibited outstanding catalytic activity for the selective conversion of glycerol towards valuable glycolic acid, eliminating the addition of extra inorganic base. As high as 71.8% yield of glycolic acid was achieved, the highest value to date as far as we know. In combination of experiment and DFT calculations, it was revealed that Cu, Mg species in catalyst enabled the relay catalysis for the cascade reactions in glycerol transformation. Cu species in catalyst dominated the first dehydrogenation reaction of glycerol to glyceraldehyde, which was promoted by Mg species. Mg species followed to catalyze the next cleavage of C2-C3 bond in glyceraldehyde to generate glycolaldehyde. The final oxidation of glycolaldehyde to glycolic acid was achieved by the catalysis of Cu species. This relay catalysis of Cu1Mg4 catalyst significantly inhibited the formation of glyceric acid and lactic acid by-products, thereby enabling the selective generation of glycolic acid.

The depolymerization of hemicellulose is essential in the downstream processing of biomass within a biorefinery, with the search for energy efficient selective pathways for its conversion presenting a significant challenge. Herein, the process of NaCl promoted depolymerization of xylo-oligomers to xylose through use of seawater and NaCl, under microwave hydrolytic conditions, is investigated by systematic kinetic study assisted by deuterated agents. It was found that NaCl shortened the reaction time (10 min in NaCl–H2O vs 60 min in H2O at 180 °C) to obtain the maximum yield of xylose (about 90 wt %) without significant secondary reaction products formed. NaCl was observed to generate acidic products from residual xylose structure, rate limiting the process, but providing acids that simultaneously catalyzed the depolymerization of xylose-oligomers. It was also found that Cl– cleaved the hydrogen bonding in xylo-oligomers, releasing separated xylo-oligomer chains and enhancing the interaction of H+ with xyl...

The unique properties of rare earth metal offer attractive potentials for the application as catalyst in biomass valorization. In present work, we found that rare earth metal ions exhibited specific catalytic activity for lactic acid production from biomass, giving 75.9% and 71.0% carbon molar yield of lactic acid from glucose and furfural residue, respectively. The activity of lanthanide(III) ions increased monotonically with the atomic number, as well as the decreasing ionic radius, from La3+ to Lu3+. The increasing oxidation potential with atomic number might facilitate the disproportionation reaction in glucose conversion via an intramolecular H-shift. DFT calculation further revealed that smaller ionic radius of lanthanide(III) ions led to stronger interaction between lanthanide(III) ions and glucose/fructose, as well as the less composition of 4f in LUMO that enabled more activation of glucose. More importantly, lanthanide(III) with smaller ionic radius exhibited higher electron-withdrawing ability from the oxygen atom in -C = O. This enhanced the electrophilicity of C2, C3, and C4 atoms, and led to the more exposure especially for C4 atom, thereby significantly weakening C3-C4 bond. In addition to the increasing orbital-stabilization ability at the bond-breaking site in the corresponding transition state with atomic number, the energy barrier for C3-C4 cleavage in fructose was greatly reduced by heavy lanthanide(III) ions. These factors contributed to the special activity for lactic acid formation from biomass. The insights in this work might give some useful clues for the widespread application of rare earth metal in biomass valorization.

The mechanism and selectivity of the asymmetric cycloaddition reactions of 3-vinylindole towards methyleneindolinone (Diels–Alder reaction) or ketimine (aza-Diels–Alder reaction) were investigated theoretically by DFT and ONIOM methods. The non-catalytic DA reaction occurred in a two-stage one-step mechanism with the energy barriers of 17.0–29.6 kcal mol−1. Reactivity index analysis indicated that the cycloaddition tended to occur by the most nucleophilic terminal C4 center in 3-vinylindole and the most electrophilic Cβ center in methyleneindolinone with lower activation energies, which accounted for the regioseletivity observed in experiment. For non-catalytic reactions, the slightly exo-preference stemmed from the stabilizing π-π stacking of two indole rings in substrates. In the presence of chiral N,N'-dioxide-Ni(II) complex, the bulky ortho-iPr group in aniline of ligand provided sufficient steric shielding around dienophile from the si-face attack in Diels–Alder reaction or re-face attack in aza-Diels–Alder reaction by diene, resulting in predominant products with excellent enantioselectivity (the favorable re-face attack in Diels–Alder reaction or si-face attack in aza-Diels–Alder reaction). A “pocket-like” chiral cavity constructed by chiral catalyst enhanced exo-diastereofacial selectivity significantly by maximizing the overlap of the two indole rings of substrates to avoid unfavorable steric repulsion between indole ring of 3-vinylindole and chiral ligand. Compared with catalytic aza-Diels–Alder reaction of 3-vinylindole and ketimine, the improved catalytic activity of chiral N,N'-dioxide-Ni(II) catalyst in Diels–Alder reaction of 3-vinylindole with methyleneindolinone contributed to the high turnover frequency (TOF = 1.05 × 106 s−1). These results were in good agreement with experimental observations.

A two-step method was adopted to produce furfural from the selective dissolution and conversion of hemicellulose in pubescens. First, in GVL(γ-valerolactone)-H2O co-solvent at 160 °C, H2O promoted the cleavage of chemical bonds linking hemicellulose, lignin, and cellulose, and GVL further helped the co-dissolution of hemicellulose (93.6 wt %) and lignin derivatives (80.2 wt %), leaving a high purity cellulose (83.3 wt %). Heating to 200 °C, the liquid system obtained with NaCl and THF added, achieved the maximum yield of 76.9 mol % with 82.2% selectivity to furfural based on the moles of converted hemicellulose using a 5 wt % pubescens to solvent ratio. It was demonstrated that NaCl with GVL promoted the depolymerization of oligomers to small molecular products (Mw < 150 Da), while the co-contribution of NaCl and co-solvent improved the selectivity to furfural. Cl– could interact strongly with C-OH-2,3,4 of the xylose unit, and the dehydration of xylose to form furfural might first occur on C-OH-4 of xylo...

Little is known about the detailed structural information at the interface of Ptn cluster and γ-Al2O3(001) surface, which plays an important role in the dehydrogenation and cracking of hydrocarbons. Here, the nucleation and growth of Ptn (n = 1–8, 13) clusters on a γ-Al2O3(001) surface have been examined using density functional theory. For the most stable configuration Ptn/γ-Al2O3(001) (n = 1–8, 13), Ptn clusters bond to the γ-Al2O3(001) surface through Pt–O and Pt–Al bonds at the expense of electron density of the Ptn cluster. With the increase in the Ptn cluster size, both the metal–support interaction and the nucleation energies exhibit an odd–even oscillation pattern, which are lower for an even Ptn cluster size than those for its adjacent odd ones. Both the metal–surface and metal–metal interactions are competitive, which control the nanoparticle morphology transition from two-dimension (2D) to three-dimension (3D). On the γ-Al2O3(001) surface, when the metal–support interaction governs, smaller clu...

Low-temperature torrefaction of pubescens was studied by one-step (RT–200 °C) and two-step (RT–120 °C first, and then 120–200 °C) ways. For one-step torrefaction, the cracking of intermolecular and intramolecular hydrogen bonds in cellulose promoted the formation of oligosaccharide, anhydrosugar, and levoglucosan intermediates with monosaccharide, carboxylic acid, furans, etc. The oligomers with 4-O-5, β-O-4 linkages were mainly derived from the cleavage of C–O–C bonds between lignin and cellulose, and p-hydoxyphenyl (H), ferulate (F) intermediates were derived from the cracking of β-O-4 and Cα–Cβ in lignin. In two-step torrefaction, the first step (RT–120 °C) tended to generate the intermediates of oligosaccharide, levoglucosan and pyranose, which mainly derived from the cleavage of intermolecular hydrogen bonds or ether bonds in amorphous cellulose. The lignin-based oligomers with 4-O-5 and β-O-4 linkages were mainly derived from the cracking of β-O-4 and dehydration. For the second step (120–200 °C), t...