Hydrogenation Of Cellulose Research Articles

Direct Hydrogenolysis of Cellulose to Methane Utilizing Rare‐Earth Promoted Nickel Catalysts

AbstractCellulose is one of the main components of plant matter, which makes it a viable target for biomass conversion to fuels. The direct conversion of cellulose to methane utilizing nickel‐based catalysts often has challenges associated with it. Carbon agglomeration creating nickel‐carbon nanoparticles deactivating catalytic hydrogenation of cellulose has been well reported. Utilizing rare‐earth metals as promoters increases the conversion of cellulose to methane, albeit with deactivation of the catalyst in the form of nickel‐rare‐earth‐carbon nanoparticles. Adding an additional zinc metal promoter eliminates the carbon agglomeration and allows for increased methane yields. Herein, we report an 81 % methane yield from cellulose in 48 hours utilizing a Ni/Zn/Y/Al2O3 catalyst at 225 °C and under 50 bar H2 pressure.

Optimisation of the processing conditions of hydrolytic hydrogenation of cellulose using carbon nanofiber supported Ni catalysts

The synthesis of sorbitol from cellulose over Ni catalysts is a promising valorisation route in the biorefinery scenario, applying relatively simple preparation methods and earth-abundant metals. The overall selectivity, however, depends on the kinetic control of a complex reaction network, involving the hydrolysis of cellulose to monosaccharides via cello-oligomers, glucose hydrogenation into sorbitol and hydrogenolysis side-reactions of sugars and sorbitol to low molecular weight polyols. Therein, subtle changes in the catalyst composition and process conditions might have a strong impact on the final product distribution. Driven by these challenges, this work first-time provides novel insights into the hydrothermal hydrogenation of cellulose over a carbon nanofibre supported Ni catalyst (Ni/CNF). Firstly, the impact of the duration of a ball-milling pre-treatment step and the influences of the hydrothermal time and temperature were thoroughly analysed. The experimental results obtained highlighted the importance of process control to promote the first transformation of cellulose to glucose and its subsequent hydrogenation to sorbitol to minimise the extension of side reactions. Finally, an additional study was conducted to palliate the recalcitrant nature of cellulose by decreasing mass transfer limitations to a minimum extent. This was achieved by including an additional mix-milling of the amorphous cellulose produced in the first pre-treatment with the catalyst and increasing the H2 pressure of the hydrothermal hydrogenation process. This allowed attaining a sorbitol yield as high as 62% at 190 ºC using an initial H2 pressure of 8 MPa for 26 h, which is one of the best results reported in the literature.

Efficient one-pot conversion of cellulose to sorbitol over Ni-based carbon catalysts with embedment structure

The solid catalyst for one-pot hydrolysis hydrogenation of cellulose with remarkable activity and stability has aroused increasing attention. Herein, a highly active and stable Ni based bimetallic carbon catalyst with embedment structure was prepared by a facile one-pot thermal reduction method with assistant of ethylene glycol dispersant. The effects of the metal precursor, dispersant, and noble metal doping were systematically addressed. The bimetallic Ni-Ru@MC exhibited higher catalytic capability in sorbitol production from ball-milled cellulose with yield of 67.8 % at 200 °C within 3 h, in comparison with the traditional metal supported catalysts such as Ru/MC and Ni/MC. The various characterization techniques revealed that the superior catalytic performance of Ni-Ru@MC was associated with its mesoporous structure with large surface area, small metal nanoparticles embedded in carbon, and especially a reasonable match between mild acidity and improved hydrogenation activity of catalyst. Significantly, after five consecutive cycles, the catalyst still maintained the similar metal content and the catalytic ability to fresh catalyst, owing to its distinctive embedment structure and helpful Ru doping.

CO2-assisted hydrolytic hydrogenation of cellulose and cellulose-based waste into sorbitol over commercial Ru/C

A single-step protocol was developed for the hydrolytic hydrogenation of microcrystalline cellulose into sorbitol over commercial carbon-supported Ru, in the presence of gaseous CO2 as an acid source and molecular hydrogen as a reductant.

Effects of Activated-carbon-supported Nickel on Catalytic Transfer Hydrogenation of Cellulose to Hydrocarbons in a Straight-chain Aliphatic Hydrocarbon Solvent

Effects of Activated-carbon-supported Nickel on Catalytic Transfer Hydrogenation of Cellulose to Hydrocarbons in a Straight-chain Aliphatic Hydrocarbon Solvent

Influence of the presence of impurities and of the biomass source on the performance of Ru catalysts in the hydrolytic hydrogenation of cellulose towards γ-valerolactone

γ-Valerolactone is one of the important molecules envisaged for future biorefinery schemes due to its advanced applications as a fuel or chemical. However, the direct conversion of waste, polluted lignocellulosic biomass towards γ-valerolactone still faces many challenges, notably due to the influence of impurities and of the nature of the biomass feedstock on the catalytic activity. Our work aimed at investigating the influence of both the presence of exo- and endogenic impurities and of the biomass source nature (softwood vs. hardwood) on the performances of Ru catalysts in the hydrolytic hydrogenation of cellulose towards γ-valerolactone. We identified key-factors which can be detrimental for the heterogeneous catalyst and for the process efficiency, among which the feedstock properties, its composition and the presence of reaction by-products is emphasized. Particularly, the softwood and hardwood origin of the biomass or its harvesting place – that impacts on the kind and the level of impurities – can strongly influence the reaction performance and the γ-valerolactone yield.

Selective catalytic hydrogenation of cellulose into sorbitol with Ru-based catalysts

Sorbitol is one of the platform chemicals and can be produced from various renewable and sustainable sources via different processes. Hydrothermal liquefaction is an effective and promising approach to produce sorbitol, since the subcritical reaction media and appropriate catalysts provide a selective production of platform chemicals. In this study, sorbitol was produced from different renewable sources (cellulose and glucose) in the presence of Ru-based catalysts (Ru/SiO2, Ru/AC, Ru/SBA-15, and Ru/SBA-15-SO3) under subcritical conditions. The highest cellulose conversion was achieved as 90% in the presence of Ru/SBA-15-SO3 for 1 h of reaction duration. The highest sorbitol yield (%) by hydrothermal liquefaction of cellulose was obtained as 6.2% by using Ru/AC for 1 h of reaction duration. A total of 99.9% of glucose conversion was achieved in the presence of all catalysts. The highest sorbitol yield (%) by hydrothermal liquefaction of glucose was found as 3.8% for 1 h of reaction duration. Owing to the results of GC-MS analysis, the intermediate products were identified, and, thus, a reaction pathway was proposed.

Recyclable Cu Salt-Derived Brønsted Acids for Hydrolytic Hydrogenation of Cellulose on Ru Catalyst

Bronsted acid-catalyzed hydrolysis of cellulose, the most abundant source of biomass in nature, is the critical step for its depolymerization and subsequent conversion to sugar alcohols and other i...

Hydrolytic Hydrogenation of Cellulose with the Use of the Ru-containing Polymeric Catalysts

The study presents the results of cellulose hydrolytic hydrogenation process in subcritical water in the presence of Ru-containing catalysts based on hypercrosslinked polystyrene (HPS) MN-270 and its functionalized analogues: NH2-HPS (MN-100) and SO3H-HPS (MN-500). It was shown that the replacement of the traditional support (carbon) by HPS increases the yield of the main cellulose conversion products – polyols – important intermediates for the chemical industry. The catalysts were characterized using transmission electron microscopy (TEM), high resolution TEM, and porosity measurements. Catalytic studies demonstrated that the catalyst containing 1.0% Ru and based on MN-270 is the most active. The total yield of sorbitol and mannitol was 50% on the average at 85% cellulose conversion.

High yield synthesis of hexitols and ethylene glycol through one-pot hydrolytic hydrogenation of cellulose

Catalytic valorization of biomass has gained a significant global attention in recent years. Cellulose is an interesting bio-renewable feedstock, which can be utilized to replace the fossil fuel derived chemicals to attain a sustainable bio-based economy. Our research shows a one-pot conversion of cellulose through hydrolytic hydrogenation using heteropolyacid (HPA)/zirconia and Ru/C catalyst. The developed catalytic system was found to be highly active towards selective production of hexitols and ethylene glycol. A significant improvement in the catalytic performance towards cellulose conversion was observed when the cellulose was pre-treated using ball-milling (900 rpm, 8 h), as the ball-milling significantly reduced the crystallinity index of cellulose, which decreased the recalcitrance of the cellulose structure. Almost complete conversion (100%) of cellulose was observed when the reaction was performed at 220 °C for 5 h giving hexitols and ethylene glycol yields of 26.2 and 40%, respectively. Based on a series of experiments, a possible reaction pathway was proposed which suggested heteropolyacid/zirconia catalyzed hydrolysis and retro-aldol condensation reactions, accompanying by hydrogenation with Ru/C. Interestingly, HPA immobilized on the composite catalyst shows enhanced stability and recyclability, demonstrating the utilization of a heterogeneous system for tandem conversions of biomass to renewable fuels and feedstocks.

Catalytic transfer hydrogenation of cellulose to hydrocarbons using straight-chain aliphatic hydrocarbon as a solvent

Catalytic transfer hydrogenation is effective for converting cellulose to liquid fuel. This method typically uses an alcohol or a cyclic compound as a liquid hydrogen resource. However, alcohol causes side reactions, and oxygen-containing compounds remain in liquid fuel. Cyclic compounds such as tetralin suppress side reactions, but negatively affect liquid fuel properties because of difficult cyclic compound-liquid fuel separation. Therefore, catalytic transfer hydrogenation of lignocellulose requires a hydrogen donor solvent that is easily separated or does not need to be separated from liquid fuel. Thus, we focused on the use of straight-chain aliphatic hydrocarbon as a solvent. When used with lignocellulose-based liquid fuel, straight-chain aliphatic hydrocarbon can remain in transportation fuel. In addition, a palladium catalyst added to this solvent is expected to behave as a hydrogen donor, because this catalyst dehydrogenates alkane while serving as a hydrogen resource. This expectation was investigated by using cellulose, a main component of lignocellulose, and hexadecane, as a straight-chain aliphatic hydrocarbon. Using this solvent for catalytic transfer hydrogenation resulted in suppressed formation of the solid residue and increased liquefied oil production. Because of this reaction, hexadecane dehydrogenation and the hydrogenation of ɤ-valerolactone and furfural from cellulose were promoted. The hydrocarbon (C10–44) yield in liquefied oil reached over 35 wt% of cellulose, and the liquefied oil was collected while still being mixed with hexadecane. Hexadecane served to extract the hydrocarbon derived from cellulose and acted as a hydrogen resource.

Selective catalytic hydrogenation of cellulose into sorbitol with Ru-based catalysts.

Sorbitol is one of the platform chemicals and can be produced from various renewable and sustainable sources via different processes. Hydrothermal liquefaction is an effective and promising approach to produce sorbitol, since the subcritical reaction media and appropriate catalysts provide a selective production of platform chemicals. In this study, sorbitol was produced from different renewable sources (cellulose and glucose) in the presence of Ru-based catalysts (Ru/SiO2, Ru/AC, Ru/SBA-15, and Ru/SBA-15-SO3) under subcritical conditions. The highest cellulose conversion was achieved as 90% in the presence of Ru/SBA-15-SO3 for 1 h of reaction duration. The highest sorbitol yield (%) by hydrothermal liquefaction of cellulose was obtained as 6.2% by using Ru/AC for 1 h of reaction duration. A total of 99.9% of glucose conversion was achieved in the presence of all catalysts. The highest sorbitol yield (%) by hydrothermal liquefaction of glucose was found as 3.8% for 1 h of reaction duration. Owing to the results of GC-MS analysis, the intermediate products were identified, and, thus, a reaction pathway was proposed.

Mesoporous Activated Carbon Supported Ru Catalysts to Efficiently Convert Cellulose into Sorbitol by Hydrolytic Hydrogenation

Catalysts consisting of Ru nanoparticles (1 wt%), supported on mesoporous activated carbons (ACs), were prepared and used in the one-pot hydrolytic hydrogenation of cellulose to obtain sorbitol. The carbon materials used as supports are a pristine commercial mesoporous AC (named SA), and two samples derived from it by sulfonation or oxidation treatments (named SASu and SAS, respectively). The catalysts have been thoroughly characterized regarding both surface chemistry and porosity, as well as Ru electronic state and particle size. The amount and type of surface functional groups in the carbon materials becomes modified as a result of the Ru incorporation process, while a high mesopore volume is preserved upon functionalization and Ru incorporation. The prepared catalysts have shown to be very active, with cellulose conversion close to 50% and selectivity to sorbitol above 75%. The support functionalization does not lead to an improvement of the catalysts’ behavior and, in fact, the Ru/SA catalyst is the most effective one, with about 50% yield to sorbitol, and a very low generation of by-products.

The effect of physical morphology and the chemical state of Ru on the catalytic properties of Ru–carbon for cellulose hydrolytic hydrogenation

Ru–carbon catalysts with different physical morphologies and chemical states of Ru were prepared by different methods and used to catalyze the hydrolytic hydrogenation of cellulose at high temperatures.

Catalytic Hydrogenolysis of Biomass-derived Polyhydric Compounds to C2–C3 Small- Molecule Polyols: A Review

Biomass energy has attracted much attention because of its clean and renewable characteristics. At present, C2–C3 polyols such as glycerol, 1,2-propanediol, and ethylene glycol, widely used as platforms for downstream chemicals or directly used as chemicals in diversified industries, mainly depend on the petrochemical industry. In terms of the feedstock for C2–C3 polyol production, the C3-derived glycerol is a side product during biodiesel synthesis, whereas the C5-derived xylitol and C6-derived sorbitol can be mainly obtained by hydrolysis–hydrogenation of hemicellulose and cellulose from lignocellulosic biomass, respectively. In this review, we summarize the catalysts and catalysis for selective hydrogenolysis of these polyhydric compounds to C2–C3 polyols and introduce the reaction pathways for the target polyol formation based on the C3, C5, and C6 polyhydric alcohol hydrogenolysis. Finally, state-of-the-art technologies are described and the remaining challenges and further prospects are presented in view of the technical aspects.

Direct conversion of cellulose into sorbitol catalyzed by a bifunctional catalyst

The conversion of cellulose into sorbitol has been recognized as one of most promising biomass valorization routes for the production of high added-value chemicals. In this work, Sulfonic acid-functionalized carbonized cassava dregs supported ruthenium bifunctional catalyst (Ru/CCD-SO3H) was prepared. The Ru/CCD-SO3H catalyst was employed for direct conversion of cellulose into sorbitol in a neutral aqueous solution. A sorbitol yield of 63.8% could be obtained at 180 °C for 10 h. The acidic sites and metal hydrogenation sites of the Ru/CCD-SO3H catalyst played an important role in hydrolytic hydrogenation of cellulose. Particularly, there presented a strong synergistic effect between sulfonic groups and Ru nanoparticles in conversion of cellulose into sorbitol. This synergistic effect was favorable to enhancing the sorbitol yield. Besides, the stability of Ru/CCD-SO3H catalyst was investigated under the optimal reaction conditions. The catalytic performance of catalyst was decreased after being used five times.

Carbon-Black-Supported Ru Catalysts for the Valorization of Cellulose through Hydrolytic Hydrogenation

The one-pot hydrolytic hydrogenation of cellulose (HHC) with heterogeneous catalysts is an interesting method for the synthesis of fuels and chemicals from a renewable resource like lignocellulosic biomass. Supported metal catalysts are interesting for this application because they can contain the required active sites for the two catalytic steps of the HHC reaction (hydrolysis and hydrogenation). In this work, Ru catalysts have been prepared using a commercial carbon black that has been modified by sulfonation and oxidation treatments with H2SO4 and (NH4)S2O8, respectively, in order to create acidic surface sites. The correlation between the catalysts’ properties and catalytic activity has been addressed after detailed catalyst characterization. The prepared catalysts are active for cellulose conversion, being that prepared with the carbon black treated with sulfuric acid the most selective to sorbitol (above 40%). This good behavior can be mainly explained by the suitable porous structure and surface chemistry of the carbon support together with the low content of residual chlorine.

Effect of the surface acid sites of tungsten trioxide for highly selective hydrogenation of cellulose to ethylene glycol

This work studied a facile and template-free hydrothermal route for controlled synthesis of tungsten trioxide in the form of hexagonal nanorod (h-WO3) and monoclinic nanosheet (m-WO3). The surface morphology, crystal plane, surface bound water, and surface acid sites of the two kinds of WO3 nanocrystals were investigated systematically. They were further evaluated as catalysts for selective cellulose hydrolysis. While both of them exhibited good catalytic performance, h-WO3 was found to be more preferential for ethylene glycol (EG) generation. This catalytic performance relied on both the unique active crystal surface (1 0 0) and surface binding water (WO3-H2O) formed by h-WO3 crystals, which provided more Lewis acid sites for degrading cellulose into EG. Results showed that the highest EG yield reaches 77.5% by a combination of loading 1 wt% Ru on the h-WO3 catalyst.

Magnetically Separable Ru-Containing Catalyst for Conversion of Polysaccharides

A new magnetic Ru-containing catalyst based on Fe 3 O 4 -SiO 2 particles was suggested for hydrogenation of cellulose to glycols and for hydrolytic hydrogenation of inulin to mannite. The influence of the process parameters on the selectivity for the main products was studied. In conditionsoptimal for cellulose hydrogenolysis, the total selectivity for glycols was ca. 40 % (19.1 % for ethyleneglycol, 20.9 % for propyleneglycol) at the 100 % conversion of cellulose. In hydrolytic hydrogenation of inulin, the maximal selectivity for mannite was 44.3 % at the 100 % conversion of the initial polysaccharide. The developed catalyst is stable under hydrothermal process conditions, easily separated from the reaction mixture under the action of the external magnetic field.

Hydrolytic hydrogenation of cellulose to ethylene glycol over carbon nanotubes supported Ru–W bimetallic catalysts

Ru and W mono- and bimetallic catalysts supported on carbon nanotubes were prepared and characterized by different techniques. The prepared catalysts were then tested for the one-pot conversion of cellulose to ethylene glycol. The influence of several factors, such as nature of metal, metal loading, amount of catalyst, catalytic support, hydrogen pressure, reaction temperature and stirring rate, was investigated. When Ru was incorporated into the supported tungsten catalyst a promoting effect was observed, with a great increase in the yield of ethylene glycol, which was explained by the interaction between both metals. The results showed that cellulose could be efficiently converted into ethylene glycol with a yield of 40% after just 3 h of reaction using 0.8%Ru–30%W/CNT as catalyst, at a temperature of 205 °C and H2 pressure of 50 bar. Moreover, the catalyst showed good stability after repeated use, at least up to four cycles, and no tungsten leaching to solution was observed.