Carboxymethyl cellulose nanocolloids anchored Pd(0) nanoparticles (CMC@Pd NPs): synthesis, characterization, and catalytic application in transfer hydrogenation

Current approaches, emerging developments and functional prospects for lignin-based catalysts – a review

“…112 Heterogeneous catalysts can be metal oxides, including Mo, Zr, Cu, Cr, and Zn, or supported metal zeolites, and also sulfonated resins, aluminum and silica oxides, and biomass-derived catalysts. 33,36,42,113,114 However, such systems may have lower catalytic activity and need longer reaction times and higher temperatures than homogeneous catalysts. As well, catalysts generally can exhibit limited energetic efficiency, quick catalyst deactivation, poor syngas selectivity, and the formation of undesired sub-products.…”

“…[34][35][36][37][38] More recently, the synthesis of biopolymeric heterogeneous catalysts has been seriously envisaged given the inherent biodegradability, ease of processing, recoverability, good conversion efficiency and possibility of replacing traditional catalytic systems. [39][40][41][42] Many researchers have investigated the catalytic performance of these natural polymers in multiple reactions. Cellulose, 43 chitosan, 44 glucose, 45 alginates 46 and carbon nanotubes 40 have been used as bio-based supports for different catalysts, although these materials are not yet economically sustainable.…”

“…Interestingly, polymeric matrices are beneficial supports for such implementation as they inhibit the aggregation of metal NPs. 42,131,162 Lignin, a biologically derived polyphenol, is being actively considered as an alternative to synthetic polymer substrates for heterogeneous Pd-based catalysts. Marulasiddeshwara et al used Pd-NPs immobilized on lignin (lignin@Pd-NPs) in the Mizoroki-Heck reaction in a solventfree system.…”

Cucurbit[6]uril supported β-Ni(OH)2 nanoparticles as a heterogeneous catalyst for the synthesis of quinazolines via acceptorless dehydrogenative coupling of alcohols with nitriles

“…62,63,65 The use of a heterogeneous support not only prevents the agglomeration but also facilitates a uniform dispersion of NPs. [66][67][68][69][70] Recently, heterogeneous catalysts based on supported nanoparticles and heterogenization of homogeneous systems have become efficient and selective catalysts for a series of organic reactions. [71][72][73] They are preferred due to their robustness and lower operational cost, and easier recovery from the reaction mixture allowing chemical processes to be streamlined.…”

“…62,63,65 The use of a heterogeneous support not only prevents the agglomeration but also facilitates a uniform dispersion of NPs. 66–70…”