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We report a sulfonated hydrophobic mesoporous organic polymer (MOP-SO3H) as a highly efficient heterogeneous catalyst for one-pot 5-ethoxymethylfurfural (EMF) production from fructose in ethanol solvent. MOP-SO3H was fabricated by co-polymerization of divinylbenzene (DVB) and sodium p-styrene sulfonate (SPSS) followed by ion exchange with dilute H2SO4, and its pore structure and acid density could be tuned easily by varying the mole ratio of SPSS to DVB. 31P MAS NMR analysis using trimethylphosphine oxide as a base probe molecule indicated that MOP-SO3H possessed a weaker Bronsted acid site than conventional cation-exchange resins. The superhydrophobic properties of MOP-SO3H were retained even after incorporating a greater number of sulfonic acid groups into the polymer framework, while conventional solid acid resins exhibited hydrophilic properties. MOP-SO3H exhibited a superior catalytic performance in comparison with conventional acid resins, a mesoporous acid catalyst, and homogeneous acid catalysts in EMF production from fructose. After optimization of various reaction conditions using MOP-SO3H, a high EMF yield of 72.2% at 99.3% fructose conversion was achieved at 100 °C in a very short reaction time of 5 h. Notably, MOP-SO3H showed a much higher EMF formation rate than the Amberlyst-15 catalyst (53.5 vs. 6.1 μmol g−1 min−1). This superior performance of the MOP-SO3H catalyst was attributed to its unique feature of large surface area containing a large quantity of readily accessible acid sites distributed throughout the hydrophobic polymer framework. In addition to its high catalytic activity, the notable stability of the MOP-SO3H catalyst was also confirmed by leaching and recyclability tests. Thus, owing to its excellent catalytic performance and easy scalability, MOP-SO3H can potentially be used as an industrial heterogeneous catalyst to produce EMF from various fructose-containing biomass.

Mesoporous tin oxide was prepared by template assisted and template-free methods. As-prepared materials were calcined at various temperatures to generate different nature (Bronsted and Lewis), amount and strength of acidic sites. The physico-chemical properties of the catalysts were studied by XRD, N2 sorption, pyridine-FTIR, NH3-TPD, DRS UV-vis, TGA, SEM, TEM, 1H MAS and 119Sn MAS NMR analyses. The catalytic behavior of mesoporous tin oxide catalysts was evaluated for acetalization and ketalization of glycerol with benzaldehyde and acetone respectively under solvent free conditions. The catalytic performance of mesoporous tin oxide was compared with that of other conventional solid acid catalysts namely H-ZSM-5, H-mordenite, H-beta, Al-MCM-41, Al-SBA-15 and Al-TUD-1. The efficiency of mesoporous tin oxide was also tested for cyclohexene epoxidation reaction. The catalyst prepared by template assisted method showed excellent catalytic performance compared to other catalysts due the difference in nature and amount of acidic sites in the catalyst. Meso-SnO2-T-350 was stable and reusable catalyst for four cycles without any appreciable loss in activity, and therefore it offers a good catalyst for potentially wide applications.

A sulfonic acid-functionalized mesoporous polymer (MP-SO3H) catalyst was prepared via post-synthetic modification of mesoporous polydivinylbenzene by incorporating a sulfonic acid moiety using conc. H2SO4. The synthesized materials were characterized via several physicochemical techniques and their performance was evaluated for the room-temperature liquid-phase acetalization of glycerol with acetone. The MP-SO3H catalyst performed better than other conventional solid acid catalysts, with a 94% glycerol conversion and 98.5% selectivity for solketal. The high activity of the MP-SO3H catalyst was attributed to the facile diffusion of reactants and products in the mesoporous environment as well as to the high acidity. Glycerol conversion increased with increase in the total acidity of the catalyst. In addition, the acidity and surface density of (H+) ions were found to have a direct correlation with the catalyst performance.

A bio-derived furfuryl alcohol transformation into various high-value chemicals is a growing field of interest among researchers. This study reports an exclusive investigation of the porosity and active sites responsible for the efficient alcoholysis of furfuryl alcohol to alkyl levulinate by the aid of zeolite catalyst. Alkyl levulinate is a promising platform chemical potentially used as a fuel additive and also for the production of chemicals. A detailed study using well-characterized HZSM-5 catalyst on the influence of acidity and post synthesis modification like desilication, dealumination, metal ion exchange and phosphate modification revealed the most desired type of acid sites required to catalyze this reaction. Among the HZSM-5 catalysts tested, HZSM-5 (SAR 95) showed the best performance of ≥ 99 % furfuryl alcohol conversion and 85 % butyl levulinate selectivity under optimum conditions. The catalyst exhibited good recyclability additionally addressing all the challenges reported in the previous literature fulfilling the green chemistry principles.

Metal hydroxy stannate is explored for the first time as a solid base catalyst for transesterification reactions. The catalyst was synthesized by co-precipitation method and characterized by PXRD, SEM, EDS, TGA, surface area and FT-IR measurements. In this work, we demonstrated metal hydroxy stannate as an efficient catalyst for the synthesis of biodiesel and to convert its byproduct glycerol into acetins. Performance of the catalyst was checked with both edible oil (sunflower) and non edible oils like waste cooking oil, jatropha, honge and simarouba. CaSn(OH) 6 gave high biodiesel yield with the tested oils at lower reaction temperature (65 °C). The performance of CaSn(OH) 6 was better than other solid base catalysts like CaO, MgO, Mg/Al HTc and KF/CaO. Separation of biodiesel from un-reacted oil and glycerol was carried out using solvent extraction method and isolated yield of biodiesel was calculated. Conditions like temperature, amount of catalyst and mole ratio were studied for both the reactions to get optimum yield of end products. Fuel properties of synthesized biodiesel were tested and compared with international standards. Catalyst showed good thermal stability and reusability with consistent activity for both the reactions.

The efficiency of mesoporous tin oxide as an acid catalyst in the activation of a carbonyl group through selected organic transformations involving the conversion of biomass derived molecules to value-added chemicals is reported. The mesoporous tin oxide was synthesized under ambient temperature using CTAB and was characterized by XRD, FT-IR, SEM, TEM, TGA, N2 sorption, TPD-NH3 and py-FT-IR. It was calcined at different temperatures, showing different physico-chemical properties, and exhibited a wormhole like topology with a large surface area of 160 m2 g−1. The py-FT-IR acidity measurement of the mesoporous tin oxide showed the presence of Bronsted and Lewis acid sites. These acid sites were sufficient to activate the carbonyl group of an aldehyde, a ketone, an acetic anhydride and an amide in selected important organic transformations such as Prins condensation, glycerol carbonylation with urea, ketalization of glycerol with cyclohexanone and acetylation of glycerol with acetic anhydride. In all the above catalytic processes, the mesoporous tin oxide showed superior performance compared to nano and bulk tin oxides. The mesoporous tin oxide catalyst also showed excellent recyclability and remarkable activity compared to the reported catalysts in all the reactions under study.

Mesoporous polymers (MP) were synthesized by free radical polymerization of divinylbenzene by a solvothermal method followed by sulfonic acid functionalization by a post synthetic modification with conc. H2SO4. MP-SO3H was characterized by various physicochemical techniques such as FT-IR, nitrogen sorption, CHNS analysis, acid–base titration and TGA. MP-SO3H was demonstrated to be a highly active heterogeneous acid catalyst, providing a high yielding route for the synthesis of h-GTBE through the etherification of bio-renewable glycerol with tert-butanol. MP-SO3H containing optimum acidity and a large mesoporous surface area gave 44% h-GTBE selectivity at 86% glycerol conversion under optimized reaction conditions. The catalytic performance of MP-SO3H was found to be superior over other conventional porous solid acid catalysts.