Phosphotungstic acid-functionalized magnetic nanoparticles as an efficient and recyclable catalyst for the one-pot production of biodiesel from grease via esterification and transesterification

Abstract

A novel, active, and recyclable magnetic nano-size solid acid catalyst was developed for the high-yielding transformation of waste grease to biodiesel (fatty acid methyl esters, FAMEs) via simultaneous esterification of free fatty acids (FFAs) and transesterification of triglycerides with methanol in one pot. The coreshell structured magnetic nanoparticles (MNPs) HPW-PGMA-MNPs consist of iron oxide MNPs as the core, poly(glycidyl methacrylate) (PGMA) as the shell, and phosphotungstic acid (HPW) as the surface acid group. They were conveniently prepared in a 93% yield from PGMA-MNPs via phosphonation with Na 2 HPO 4 and subsequent treatment with Na 2 WO 4 •2H 2 O under acidic conditions, allowing for in situ formation of HPW on the particle surface with a high acidity of 1.13 mmol g −1 and a particle size of 90 nm.The catalyst was fully characterized by EDX, FT-IR, FESEM, TEM, and VSM. It demonstrated a much better catalytic performance for the transesterification of triacetin and for the one-pot transformation of grease to biodiesel than commercially available solid acid catalysts such as Amberlyst 15, Purolite CT-275, and zeolite. One-pot transformation of grease (21.3 wt% FFAs) with methanol using HPW-PGMA-MNPs (4 wt %) gave a 98% FAME yield after 24 h, with 96% conversion for the esterification and >98% conversion for the transesterification. HPW-PGMA-MNPs were easily separated from the reaction mixture under a magnetic field and efficiently reused for further cycles of transformation, retaining 95% productivity in the 10 th reaction cycle. Thus, the developed magnetic nano-size solid acid catalyst is potentially useful for the green and economic production of biodiesel from waste grease. † Electronic supplementary information (ESI) available: Additional experimental procedures, characterization of MNPs, and GC chromatograms. See

Polyoxometalate-MgF2hybrids as heterogeneous solid acid catalysts for efficient biodiesel production

“…S1(a) †), suggesting that the Mg 20 -F 39 TPA-x hybrids were formed. 40 These results were in good agreement with those of XRD patterns. FT-IR spectra of Mg 20 Fig.…”

Nano La2O3 as a heterogeneous catalyst for biodiesel synthesis by transesterification of Jatropha curcas L. oil

“…Fossil fuels account for 88% of the primary energy 12 consumption [2], whereas the depletion of fossil fuels and the 13 accompanying environmental issues are becoming a serious threat 14 to humanity. In past decades, scientific researchers have made 15 great efforts to discover new viable substitutes of fossil fuels, and 16 considerable attention has been paid to the development of 17 biofuels, particularly to biodiesel [3]. Generally, biodiesel is a 18 mixture of long-chain fatty acid methyl esters (FAME) that is 19 produced from free fatty acids, vegetable oils, animal oils or waste 20 oil through esterification and/or transesterification with alcohols 21 (Fig.…”

“…In 42 fact, both esterification and transesterification can be catalysed 43 using solid acid catalysts through a one-pot method. For example, 44 12-tungstophosphoric acid (TPA) [12], phosphotungstic acid 45 functionalised magnetic nanoparticles [13], ionic liquids-FeCl 3 46 [14,15] and acidic heteropoly salts (e.g., CsHPW) [16] were 47 developed to be utilised for the catalytic transformation of waste 48 grease or high-acid value oils to biodiesel through simultaneous 49 esterification of free fatty acids (FFAs) and transesterification of 50 triglycerides with methanol in one pot. However, the reaction 51 needed a long reaction time with high reaction temperature and 52 pressure.…”

Facile route to conformal hydrotalcite coatings over complex architectures: a hierarchically ordered nanoporous base catalyst for FAME production

“…21 Isolation of the desired biodiesel product from homogeneous base catalysts (and unreacted mono-and di-alkyl glycerides and glycerol by-product) is necessary to circumvent saponification and emulsification side reactions and produce a high quality biofuel. 6 Heterogeneous, solid acid [22][23][24] and base catalysts offer facile FAME separation, eliminating the requirement for quenching steps and permitting continuous biodiesel production, 25 and a purer glycerol by-product stream for use as a commodity chemical in the food and cosmetics industry. Among solid base catalysts, hydrotalcites, [26][27][28] alkaline earth oxides [29][30][31][32][33] and alkali-doped mesoporous silicas 34 are good potential candidates for biodiesel formation under mild conditions.…”