Synthetic Niobium Oxyhydroxide as a Bifunctional Catalyst for Production of Ethers and Allyl Alcohol from Waste Glycerol

Abstract

A synthetic niobia was modified by treatment with hydrogen peroxide to be used as a catalyst for converting glycerol into petrochemical compounds. The catalytic properties of niobium oxyhydroxide were obtained by generating acidic and oxygenated groups (peroxo groups) on the solid surface. Compounds like ethers and allyl alcohol were obtained. A very active H 2 O 2 -modified catalyst showed high activity for the oxidation and dehydration of 91% of glycerol conversion using H 2 O 2 and 46% of allyl alcohol selectivity in volatile phase. The product was analyzed by gas chromatography-mass spectrometry (GC-MS), thermogravimetry-mass spectrometry (TGA-MS) and nuclear magnetic ressonance (NMR). These results strongly suggest that the reactions involve acid and oxidizing species generated after the reaction of niobium with H 2 O 2 . 1 H and 13 C multidimensional NMR spectroscopy confirmed the results obtained with GC-MS and showed the production of several compounds after niobia treatment. Keywords: nobium, oxyhydroxide, glycerol, ethers, allyl alcohol IntroductionBrazil is a country that stands out for its great capacity to produce renewable energy, starting with the Proálcool program for the use of ethanol as a fuel alternative to gasoline. 1 The country currently has a national program for the gradual inclusion of biodiesel in diesel fuel 2 (2% at the beginning of the program, 5% from 2010 and 7% nowadays).3 Biodiesel appears as a promising energy source that would cause less environmental impact, 4 especially by reducing CO 2 emissions. The most appropriate way to yield such diesel fuel is by converting the triacylglyceride structure of vegetable oils or animal fats into fatty acid mono-alkyl esters standardized as biodiesel when meeting the requirements of ASTM D 6751 and Euro norm EN 14214. 6 The production of biodiesel by transesterification of triacylglycerides yields glycerol as a byproduct. The large amounts thus produced have turned glycerol from a specialty chemical into a commodity. Unfortunately, the production of this fuel has certain limitations, such as the generation of large amounts of glycerol as a byproduct. Although glycerol is widely used as a raw material in various industrial applications, the material is nevertheless produced in much larger amounts than needed.6 However, to be used as a renewable raw material to replace petrochemicals in the production of important or promising chemical intermediates like epichlorohydrine (ECH), propylene glycol (PG), acrylic acid or 1, 3-propanediol, 7,8 the forecasted by-product volumes would be largely insufficient. Currently, the Brazilian market consumes approximately 40,000 tons year -1 of glycerol, however, the production with the introduction of B2 (2% of biodiesel in regular diesel) in 2008 was 80,000 tons year -1 of glycerol. 9 In 2014, Brazil produced 390,000 tons of crude glycerin from biodiesel. 10 This increase shows that the viability of the biodiesel program is directly related to the ability to produce economically feasible materials from ...

Niobium: The Focus on Catalytic Application in the Conversion of Biomass and Biomass Derivatives

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Unveiling the Structural and Electronic Properties of the B-Nb2O5 Surfaces and Their Interaction with H2O and H2O2

“…Hydrogen peroxide interaction with the surface of catalysts is the key point to determine further transformations and reactions with the oxidized molecule. Niobia also has been used in oxidation reactions after treatment with hydrogen peroxide (H 2 O 2 ) to generate highly oxidizing surface groups. − Ventura et al evaluated the catalytic activity of Nb 2 O 5 nanoparticles in the liquid phase oxidation of aniline with aqueous H 2 O 2 as oxidizing agent. The results evidenced high catalytic activity with total conversion of aniline at ambient condition.…”

Transition Metal Catalysts for the Glycerol Reduction: Recent Advances

“…They synthesized a niobiumvanadium-modified silicate and a niobium oxyhydroxide for the simultaneous dehydration/oxidation of GL with hydrogen peroxide at 523 K resulting in a quantitative conversion of the substrate and 14 % and 46 % AA selectivity, respectively. [47,78]…”