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Keggin heteropolyacids (HPAs) comprise a class of versatile catalysts, which have properties that can be easily adjusted through modification in their structure, such as the protons exchange, the removal or one or more MO unity (i. e., W or Mo) followed by doping with transition metals, or even less frequently, the substitution of heteroatom (i. e., P or Si). In this work, these effects were assessed by modifying the structure of silicotungstic acid (i. e., H4SiW12O40) with Co2+ cations. A series of Cobalt‐polyoxometalates (i. e., Co2SiW12O40, K6CoW12O40, K8SiW11O39, K6SiCoW11O39, K8CoW11CoO39) were synthesized and catalytically evaluated in furfural acetalization with alkyl alcohols. Spectroscopy analyses (i. e., UV‐Vis, FT‐IR, EDS), powder X‐ray diffraction patterns, scan electronic microscopy images, surface area, porosity, and thermal analyses provided the main physicochemical properties of the synthesized salts. Acidity properties were assessed by potentiometric titration and adsorbed Py‐FT‐IR spectroscopy. The impact of temperature, nature, and catalyst loading, and type of alcohol were investigated. The K6CoW12O40 salt was the most active and selective catalyst. We paid special attention to correlating the catalyst activity with its composition and properties. [ABSTRACT FROM AUTHOR]

Keywords: acetalization; biomass; Cobalt (II) polyoxometalates; silicotungstate salts; furfural EN acetalization biomass Cobalt (II) polyoxometalates silicotungstate salts furfural 1 1 1 10/28/22 20221026 NES 221026 GRAPH Biomass, Cobalt (II) polyoxometalates, acetalization, silicotungstate salts, furfural. [Extracted from the article]

[Display omitted] • H 3-x Sn x/2 PMo 12 O 40 -catalyzed glycerol etherification was assessed (x = 0.0, 1.0, 2.0, 3.0). • Analyses of TG/DSC, EDS/MEV, BET, DRX characterized Sn(II) heteropoly salts. • NH 3 -TPD and adsorbed pyridine FT-IR showed bifunctional Sn 3/2 PMo 12 O 40 catalyst. • Annual capacity of 30,000 ton3 with a return on investment (ROI) of 30.7%. In this work, phosphomolybdic acid salts were synthesized exchanging their protons by the Sn(II) cations (i.e., H 3-x Sn x/2 PMo 12 O 40 ; x = 0.0, 1.0, 2.0, 3.0), and evaluated in the etherification reactions of glycerol with tert-butyl alcohol (TBA). The catalytic activity of the phosphomolybdate salts containing a variable load of Sn(II) ions was further compared to phosphotungstic and silicotungstic acid salts (i.e., H 3-x Sn x/2 PW 12 O 40 ; x = 0.0, 1.0, 2.0, 3.0 and H 4-x Sn x/2 PW 12 O 40 ; x = 0.0, 1.0, 2.0, 4.0, respectively). The integrity of the Keggin anion after the synthesis was confirmed by infrared spectroscopy analysis. Physical properties were determined through thermal analyses, powder X-Rays diffraction patterns, N 2 adsorption-desorption isotherms, and scanning electron microscopy. The acidity properties were analyzed by adsorbed pyridine FT-IR spectroscopy, NH 3 -programmed-temperature desorption, and potentiometric titration. Among all the Sn(II) heteropoly salts tested, the Sn 3 PMo 12 O 40 was the most active and selective catalyst toward glyceryl ethers. The highest activity of Sn 3 PMo 12 O 40 was assigned to the greater Lewis acidity strength. Modeling, simulation, and economic analysis allowed to evaluate the viability of the process. An annual capacity of 30,000 metric tons was developed, and the process is feasible with a return on investment (ROI) of 30.7%. [ABSTRACT FROM AUTHOR]