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CO2-assisted dehydrogenation of benzyl alcohol to benzaldehyde over Cu nanoparticles dispersed on CeO2 was reported. Cu nanoparticles with an average size of ∼11.4 nm dispersed over CeO2 cubes were...

The production of drop-in chemicals from biomass within the limits of process economics is always attractive for sustainable growth. Most of the biomass conversion processes involve hydrogenation reactions to produce value-added chemicals and fuels. Despite the products’ yields, the reaction parameters include high reaction temperatures, pressurized H2 reaction systems, and the need of noble metal catalysts could create intensive capital investments for hydrogenation reactions. To avoid or minimize these impediments, catalytic transfer hydrogenation seems to be a promising tool for up-grading biomass to desirable fuels and chemicals. It offers external H2-free process and the reactions can be performed at mild reaction conditions. In this chapter, the production of two important biomass-derived chemicals, namely γ-valerolactone (from levulinic acid or its esters) and furfuryl alcohol (from furfural) via catalytic transfer hydrogenation, is discussed. Various advanced catalytic materials and their design and features are also discussed and correlated with transfer hydrogenation activity.

Here, we report an inexpensive, versatile, and environmentally benign biomass waste rice husk derived amorphous silica-supported palladium (PdNPs/RH-SiO2) nano-catalyst for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions. The proposed catalyst was prepared in two steps. In the first step, amorphous SiO2 obtained by calcination of rice husk and the following deposition of palladium nanoparticles by using the chemical reduction method in the second step. The physico-chemical properties of the catalysts were investigated by N2 adsorption–desorption, XRD, XPS, 29Si CP-MAS NMR, and TEM analysis. The palladium content in the catalysts has been determined by ICP-OES analysis. The 1% PdNPs/RH-SiO2 exhibited excellent catalytic performance for Suzuki–Miyaura and Heck–Mizoroki C–C cross-coupling reactions to produce biaryl and stilbene compounds with >99% selectivity and excellent TON values (529 and 524). Furthermore, the catalyst is repeatedly used for four consecutive cycles without a significant drop in the yield.

Iron oxide (FeOx) supported on 1:3 carbon-alumina (ICA) was prepared by wet impregnation method. Oxidized and reduced forms of Fe in ICA catalyst were achieved by diluted H2O2 and hydrazine hydrate treatments, respectively. Three different oxidation states of Fe present in magnetite (Fe2+ and Fe3+), hematite (Fe3+) and wustite (Fe2+) were confirmed by XPS, powder-XRD, H2-TPR, TGA, NH3-TPD and N2-physisorption analysis. Among the synthesized catalysts, in comparison with hematite and wustite phases, magnetite phase offered high catalytic activity in ethylbenzene dehydrogenation reaction. The presence of CO2 in the reaction mixture was found to leave intact the activated carbon support structure.

Despite the enormous interest raised in a few industrially important reactions (ammonia synthesis and decomposition, hydrodenitrogenation, hydrodesulphurization, hydrogenation, dehydrogenation and reforming reactions) molybdenum nitrides are the less studied class of compounds and fascinated keen attention to replace the noble metals as the catalytic activities of these materials resembles or exceed to that of noble metals. Out of the above said reactions nitride catalysts have been extensively studied for ammonia synthesis and decomposition reactions due to the presence of active molybdenum–nitrogen sites. Nitride materials can be produced by incorporation of nitrogen into the interstitial position of the early transition metals by dissimilar methods at higher temperatures. The present review focus mainly on the synthesis of binary and ternary molybdenum nitrides via different routes and application of these materials to the industrial catalytic reactions.

The present work is aimed to produce γ-valerolactone (GVL) from ethyl levulinate hydrogenation over non-noble metal cobalt catalysts at atmospheric pressure in continuous process. Various supported (SBA-15, SiO2, Al2O3, ZrO2, and TiO2) cobalt catalysts were prepared by wet impregnation method and characterized by XRD, N2 physisorption, SEM, TEM, NH3-TPD, H2-TPR and H2-pulse chemisorption techniques. The yield of GVL follows the trend Co/SBA-15 > Co/SiO2 > Co/Al2O3 > Co/ZrO2 > Co/TiO2 similar to trend in active Co metal surface area. The catalytic activity of the supported Co catalyst is strongly influenced by the dispersion and particle size of the Co.

Aiming at synthesizing alkyl levulinates via alcoholysis of furfuryl alcohol in continuous mode for the first time an attempt is made using cheapest and eco-friendly solid acid catalysts. Different silica supported solid acid catalysts containing the oxides of aluminium, tungsten, zirconium and titanium have been prepared. The nature, number and strength of surface acidic sites were evaluated by DRIFT spectroscopy with pyridine adsorption and NH3-TPD and also structural and textural features of the catalysts have been investigated by XRD and BET surface area techniques. Al2O3/SiO2 catalyst exhibited better activity with 100% conversion of furfuryl alcohol and 92.8% selectivity of methyl levulinate, which may be due to more number of surface acidic sites with large number of weak Lewis acidic sites. The catalytic activity of these solid acid catalysts is as follows: Al2O3/SiO2 > ZrO2/SiO2 > WO3/SiO2 > TiO2/SiO2. This is well correlated with the number of surface acidic sites. The stable catalytic activity during the 10 h time-on-stream study confirmed the sturdiness of Al2O3/SiO2 catalyst and also it is active for the selective formation of ethyl, n-propyl, n-butyl levulinates.

Highly dispersed cobalt nanoparticles were prepared over mesoporous silica with different pore structures (2D-hexagonal COK-12 and 3D-cubic SBA-16). These catalysts were evaluated for gas phase hydrogenation of nitrobenzene to aniline at atmospheric H2 pressure. A combination of catalytic activity and characterization results were assessed to establish the role of the support pore structure on hydrogenation activity. XRD, N2-physisorption, SEM and TEM analysis confirmed the presence of mesoporous structures in the supported cobalt catalysts. H2-TPR, H2-pulse chemisorption and TEM studies demonstrated higher dispersion of cobalt nanoparticles in Co/SBA-16 than in the Co/COK-12 catalyst. During the time-on-stream study the Co/SBA-16 catalyst experienced a gradual deactivation whereas the Co/COK-12 catalyst exhibited constant catalytic performance with respect to the hydrogenation of nitrobenzene. The interconnected cage type pores in Co/SBA-16 catalyst allowed the product molecules to participate in further reactions. This resulted in the formation of condensed products and coke deposition. The Co/SBA-16 catalyst was rapidly deactivated due to pore blocking through coke deposition. N2-Physisorption, TGA, H2-TPR and CHNS elemental analysis of spent catalysts confirmed the severe coke deposition in the Co/SBA-16 catalyst compared to the Co/COK-12 catalyst.

Since 5 % Co/SiO2 catalysts exhibited good activity in nitrobenzene hydrogenation when compared other supported (Al2O3, ZrO2, TiO2) catalysts(SI), effect of Co loading on SiO2 support against aniline synthesis was studied in vapour phase conditions. Variation of Co loading revealed that 5 % Co/SiO2 is a better catalyst in terms of nitrobenzene hydrogenation activity. Smaller Co particle size with good number of active sites are helpful in exhibiting good activity by this catalyst .However this catalyst suffers activity loss after 7th hour due to coking. In order to sustain the activity for longer duration SiO2 surface was coated with carbon prior to deposition of Co and found that this Co/C-SiO2 catalyst exhibited high and steady activity during the time on steam study.

With the aim of producing high potential biomass derived chemicals and biofuels in safe environment, carbon–MgO composite (MgO-CX, X = wt% of carbon content) eco-friendly metal-free catalysts have been prepared via in-situ transformation technique using rice grain as carbon precursor. All these MgO-CX catalysts are characterized by X-ray diffraction, BET surface area, temperature programmed desorption of CO2, Raman and FT-IR. The MgO-CX catalysts are subjected to catalytic transfer hydrogenation of furfural into furfuryl alcohol, using isopropanol as H-donor in continuous process at atmospheric pressure. MgO-C68 is the best catalyst of this series, which exhibited 100% conversion of furfural with 98% selectivity of furfuryl alcohol. The existence of large number of suitable basic sites on the surface of MgO-C68 catalyst is responsible for its superior catalytic activity and durability.

Alkyl levulinates are promising renewable chemicals in the field of transportation fuels. In this work, the production of alkyl levulinates from furfuryl alcohol was investigated over a series of Al2O3/SBA-15 catalysts prepared by the wet impregnation method. The physicochemical features of the synthesized catalysts were characterized by X-ray diffraction, N2-physisorption, SEM, TEM, temperature-programmed desorption of ammonia, pyridine-adsorbed FT-IR and ICP-OES techniques. These analyses showed that the Al2O3/SBA-15 catalysts maintained the mesoporous structure of parent SBA-15 and that alumina particles were highly dispersed in the uniform pore channels of SBA-15. Al2O3 impregnation over SBA-15 resulted in enhanced acidity and the easy accessibility of active sites to reactants. Among the catalysts, 20 wt% Al2O3/SBA-15 catalyst exhibited the best activity in the alcoholysis of furfuryl alcohol with n-butanol, giving 94% selectivity toward n-butyl levulinate in a batch process. The reaction proceeded via formation of intermediates 2-butoxymethylfuran and 5,5-dibutoxy-2-pentanone, followed by conversion to n-butyl levulinate. The effects of various reaction parameters, including alumina loading, temperature, catalyst amount, n-butanol volume, and different alcohols, were studied. Catalyst recyclability was tested and the spent catalyst characterized. The 20 wt% Al2O3/SBA-15 catalyst was also active in n-butyl levulinate synthesis using a continuous process.

The present work highlights the application of solid acid catalyst to produce alkyl levulinate from levulinic acid in continuous mode under vapor phase conditions. In this context, tungsten oxide incorporated SBA-16 catalysts were prepared by one pot direct synthesis method and evaluated for the titled reaction. Under optimized reaction conditions, 3 wt% WO 3 -SBA-16 catalyst delivered complete conversion of levulinic acid with 95% selectivity towards ethyl levulinate. The synthesized catalysts were characterized to know the physico-chemical features by various techniques, namely, X-ray diffraction, N 2 physisorption, temperature programmed reduction of hydrogen (H 2 -TPR), temperature programmed desorption of ammonia (NH 3 -TPD), DR-UV–vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The characterization results suggest that, the superior catalytic activity can be ascribed due to the enhanced acidity of SBA-16 obtained through incorporation of tungsten oxide and easy of accessibility for the dispersed active sites through uniform pore channels. The constant catalytic activity in 10 h time on study shows the sturdiness of the catalyst and the spent catalyst can be regenerated several times. Moreover, various alkyl levulinates (methyl, n -propyl, and n -butyl) were synthesized with more than 90% selectivity over this catalyst.

With an aim to establish supported non-noble Co metal catalysts for production of a promising fuel and fuel additive γ-valerolactone (GVL) at ambient pressure in continuous mode, Co/γ-Al2O3 and bimetallic Ni-Co/γ-Al2O3 catalysts were prepared and their catalytic activities vs. catalytic features were correlated. Ni-Co/γ-Al2O3 catalyst exhibited GVL productivity of 1.125 kgGVL.kgcatalyst−1h−1 which is relatively higher than Co/γ-Al2O3 catalyst. Ni-Co/γ-Al2O3 catalyst is stable during 12 h time-on-stream studies while Co/γ-Al2O3 catalyst suffers from deactivation. The addition of Ni to Co/γ-Al2O3 augments the resultant bimetallic catalyst activity and coke resistance capacity. As evidenced from XRD, H2-TPR, XPS analyses the addition of Ni to Co/γ-Al2O3 results in formation of Ni-Co alloy in the bimetallic catalysts. H2-pulse chemisorption studies and TEM analyses illustrate formation of smaller particles in bimetallic Ni-Co/γ-Al2O3 catalyst which in turn influenced the rate of formation of GVL. From TGA of spent catalysts, the carbon deposition rate is found to be decreased in the case of Ni-Co/γ-Al2O3 catalyst (0.43 mmol.gcat−1.h−1) than Co/γ-Al2O3 catalyst (1.014 mmol.gcat−1.h−1). Among the feedstocks of GVL i.e. levulinic acid, methyl levulinate, ethyl levulinate, ethyl levulinate is found to be prominent in constantly yielding GVL during 24 h study over bimetallic Ni-Co/γ-Al2O3 catalyst.

With an aim to set up acid-base functionalities in mesoporous SBA-15, herein we report one pot hydrothermal synthetic strategy to incorporate LaPO4 into SBA-15 (LaP-SBA-15). ICP-OES and EDX results confirmed successful incorporation of large amount of LaPO4 in SBA-15. The small angle XRD, N2-isotherms and TEM studies unveiled the presence of ordered mesoporous and its characteristic features in LaP-SBA-15 catalysts. The incorporated LaPO4 is existed in monoclinic phase which is authenticated by wide angle XRD and FT-IR results. In addition to this, electron microscope images of LaP-SBA-15 catalysts clearly illustrate the crystalline growth of monoclinic LaPO4 nanoparticles across the hexagonal mesopore channels of SBA-15. NH3/CO2 -TPD demonstrated existence of both surface acidic and basic sites which are imparted to SBA-15 through LaPO4 incorporation. LaP-SBA-15 catalysts have been evaluated for the selective O-alkylation of phenol with methanol in continuous process. LaP-SBA-15 catalysts offer excellent catalytic activity and selectivity towards anisole. The surface acidic and basic sites could be tuned by adjusting the LaPO4 content, which leads to the tunable selectivity in the O-methylation of phenol. Especially, 30 wt % LaP-SBA- 15 catalyst exhibited constant selectivity to anisole up to 16 h of time-on-stream. This superior catalytic performance of 30 wt% LaP-SBA-15 catalyst is attributed to dispersion of balanced amount weak acidic and moderate basic sites through mesopores and the transportation of reactant and product molecules through uniform channels of SBA-15 containing LaPO4.

A series of mesoporous silica KIT-6 supported Ni catalysts were prepared by wet impregnation method and evaluated for the lignin-derived diphenyl ether hydrogenolysis under atmospheric pressure in the continuous process. All the catalysts were characterized by powder XRD, $$\hbox {N}_{2}$$ -physisorption, SEM, TEM, $$\hbox {H}_{2}$$ -TPR analysis $$\hbox {H}_{2}$$ -pulse chemisorption studies. Among the catalysts, 20-wt%-Ni/KIT-6 exhibited better activity and selectivity due to the well dispersion of Ni particles through uniform pore channel of KIT-6. 20Ni/KIT-6 shows consistent selectivity to aromatics with a decrease in conversion of diphenyl ether during the time on stream studies. SynopsisNi/KIT-6 catalysts are active in cleavage of $$\hbox {C}_{\mathrm{aryl}}$$ -O- $$\hbox {C}_{\mathrm{aryl}}$$ bond of Diphenyl ether, a lignin model compound, in a continuous process at atmospheric pressure

γ-Valerolactone is a promising renewable feedstock for the production of fuels and industrial chemicals. In this work, SBA-15 supported ZrO2 catalysts prepared by a wet impregnation method with various ZrO2 loadings ranging from 10 to 30 weight% have been studied for the production of γ-valerolactone from levulinic acid via catalytic transfer hydrogenation and cyclization with isopropanol as a H-donor in the vapour phase at atmospheric pressure. Among the catalysts, 25 weight% ZrO2/SBA-15 has been identified as an efficient catalyst for the transfer hydrogenation, delivering 100% conversion of levulinic acid with 93% selectivity towards γ-valerolactone. The physicochemical characteristics of these catalysts were achieved by X-ray diffraction, BET surface area, pore size distribution, UV-visible spectroscopy, temperature-programmed desorption of ammonia, SEM, TEM and ICP-OES techniques. The characterization studies divulge the presence of ZrO2 with well-dispersed acidic sites, enhanced surface area, and ease of accessibility for the active sites within the uniform pore channels, and these engendered the excellent catalytic performance with low molar ratios 1 : 7 (levulinic acid : isopropanol). Moreover, the catalyst showed sturdiness during 20 hours on-stream study.

This work aims to produce hydrocinnamaldehyde via selective C C bond hydrogenation of cinnamaldehyde via transfer hydrogenation catalyzed by supported Cu catalysts. The catalytic activity and characterization results demonstrated that conversion of cinnamaldehyde and selectivity to hydrocinnamaldehyde is an integrated result of active Cu metal surface area and nature of support material. In the case of Cu/SiO2 catalysts, the rate of formation of hydrocinnamaldehyde was linearly dependent on the active Cu metal surface area. A maximum rate of formation of hydrocinnamaldehyde 167.82 μmol.g−1.s-1 was obtained at an active Cu metal surface area of 6.1 m2.gcat-1 over 20 wt. % Cu/SiO2 catalyst. While in the case of other supported Cu catalysts (Cu/MgO, Cu/ZrO2 and Cu/γ-Al2O3) along with the active Cu metal surface area, the surface acidity and basicity governed the selectivity of hydrocinnamaldehyde. The rate of formation of hydrocinnamaldehyde followed the trend Cu/SiO2 >Cu/Al2O3 >Cu/MgO > Cu/ZrO2. Unlike Cu/SiO2 catalyst, the competitive adsorption of C C and CO bonds over these (Al2O3, MgO and ZrO2) supported Cu catalysts altered the selectivity of hydrocinnamaldehyde. Cu/SiO2 catalyst was superior in selective C C hydrogenation of α, β-unsaturated carbonyl compounds via transfer hydrogenation. Cyclohexenone, isophorone and crotonaldehyde were selectively converted into their saturated carbonyl compounds.

A RhNPs/SBA-NH2 catalyst with

The present work highlights the influence of ceria over vanadia/alumina for the oxidative dehydrogenation of ethylbenzene to styrene with CO2 as a soft oxidant. Various weight loadings (0, 3, 5, and 7 %) of ceria were incorporated into 10wt % V2O5/Al2O3 catalyst by wet impregnation process. Structural and textural characterizations of the catalysts were performed by means of powder X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of CO2, N2 adsorption–desorption analysis. Over 10 % V2O5/Al2O3, ethylbenzene conversion decreases from 62 to 49 % in a spam of 12 h. Ceria-incorporated catalyst (3 % CeO2/10 % V2O5/Al2O3) showed steady ethylbenzene conversion of nearly 65 % with a styrene selectivity of 96 % for a period of 12 h time. Improved catalytic activity observed on this catalyst can be attributed to the increase in the number of redox/active VOx species after incorporation of ceria. The redox properties of 3 % CeO2/10 % V2O5/Al2O3 and 10wt % V2O5/Al2O3 were examined by reaction of CO2 in pulses on to the partially reduced catalysts. The spent catalysts were characterized using XRD & TPR analysis to assess the reason for the deactivation of catalysts.