Functionalized Biochar with Superacidity and Hydrophobicity as a Highly Efficient Catalyst in the Synthesis of Renewable High-Density Fuels

Abstract

Developing sulfonic-acid-supported catalysts with superacidity and hydrophobicity is of great importance for many acid-catalyzed reactions where H 2 O is generated. Herein, a novel hydrophobic superacidic biochar is first reported via a diazo grafting method using halogen-substituted aminobenzenesulfonic acids and 4-tert-butylaniline as sulfonating and hydrophobic reagents, respectively. The resultant biochar has a high Brunauer−Emmett− Teller (BET) surface area (400−700 m 2 •g −1 ), acid concentration (up to 1.5 mmol•g −1 ), and H 2 O contact angle (above 134°). The synergistic effect of superacidity and hydrophobicity greatly improves the catalytic alkylation reactions of 4-ethylphenol-phenylmethanol and 2-methylfuran-cyclic ketones for the synthesis of renewable high-density fuels. The hydrophobic superacidic biochar shows higher catalytic conversion and selectivity than those of its counterparts without hydrophobicity or superacidity. Meanwhile, it is also far superior to commercial Amberlyst-15 and the traditional sulfonated biochar. Finally, the catalyst is stable without obvious activity reduction after cycling.

FeSTi Superacid Catalyst for NH3-SCR with Superior Resistance to Metal Poisons in Flue Gas

“…, Lewis acid sites). Upon adsorbing water, these Lewis sites are converted to Brønsted acid sites via the formation of hydroxyl groups in conjunction with the ionization of water. − As shown in Figure a, the fresh FeSTi catalyst exhibited two NH 3 desorption stages. The initial broad peak centered at approximately 175 °C is primarily ascribed to physisorbed NH 3 and NH 3 adsorbed on weak acid sites, while the latter peak centered at about 490 °C primarily resulted from NH 3 associated with strong acid sites .…”

Preparation of Hydrophobic Acidic Metal–Organic Frameworks and Their Application for 5-Hydroxymethylfurfural Synthesis

“…Sulfonic acid-functionalized solid catalysts have been envisaged as interesting alternatives to classical inorganic acid solids . Normally, porous materials (such as zeolites, organic mesoporous silicon, carbons, resins, and metal–organic frameworks (MOFs)) with supported sulfonic acid exhibit considerable activity due to their large surface areas and the high accessibility of their active sites. − However, in most cases, the water in the reaction system (as a solvent or byproduct or included in commercial reagents) can partially or completely deactivate solid acid catalysts by coordinating to the acid sites and forming acid–base adducts, which reduces the catalytic activity. , In addition, water can trigger some side reactions through the coadsorption of a reactant or product at the SO 3 H sites. Typically, as a widely used platform chemical in biomass transformation, 5-hydroxymethylfurfural (HMF) plays an important role in the synthesis of biofuels (such as C9–C18 alkanes) and various fine compounds (such as 2,5-furandicarboxylic acid, 2,5-dihydroxymethyltetrahydrofuran, and linear alcohols). − The production of HMF is the key for the efficient utilization of biomass resources.…”

Synthesis of ethyl levulinate from cellulose over a double acid site catalyst

“…Both materials displayed double peaks in the range of 2-10 nm along with a wide distribution over the range of 10-50 nm, because sulfonic acid groups and Al 2 (SO 4 ) 3 occupied a portion of the pore space in the OOMC and destroyed part of the pore walls. 33,34 Compared with the OOMC, the OOMC-SO 3 H and Al-OCS-0.1 samples showed a shift in the peak distribution, incremental pore volume decreases and wide peaks. The BET surface areas of the OOMC-SO 3 H and Al-OCS-0.1 were also decreased while the average pore sizes were increased (Table 1).…”