Siliceous tin phosphates as effective bifunctional catalysts for selective conversion of dihydroxyacetone to lactic acid

Abstract

Siliceous tin phosphates were demonstrated to be efficient Brønsted–Lewis acid bifunctional catalysts during the conversion of triose sugars to LA under hydrothermal conditions.

Dihydroxyacetone conversion into lactic acid in an aqueous medium in the presence of metal salts: influence of the ionic thermodynamic equilibrium on the reaction performance

“…For a kinetic modeling of DHA conversion to LA, the impact of DHA isomerization to glyceraldehyde (GLY) has to be taken into account. Different studies in the literature [8][9][10]20 compare batch concentration profiles when DHA or GLY are used as the starting material and all lead to the same conclusions: GLY isomerizes to DHA very quickly, the direct conversion of GLY to PA being negligible. Moreover, Liang et al 26 reported experimental and calculated free enthalpies of reaction in the range of 2.3 to 10.9 kJ/mol for isomerization of DHA to GLY, confirming that the conversion of DHA to GLY is thermodynamically unfavourable.…”

“…the catalytic conversion of DHA into LA. Several homogeneous catalysts such as metal salts 7,8 or heterogeneous catalysts such as zeolites [9][10][11] and tin phosphates 9,10 were proposed.…”

“…It is well admitted that this reaction proceeds in two steps: 5,8,9,[11][12][13][14][15][16][17][18][19][20] (i) DHA is first converted into pyruvaldehyde (PA) by successive keto-enol tautomerization and dehydration; 8,9,16,18 this reaction is described to be catalyzed by both Lewis and Brønsted acids. 8,11,18 (ii) Rehydratation of PA followed by a 1,2-hydride shift yields LA; for this second step, Lewis acids are believed to lead to higher catalytic performances than Brønsted acids.…”

Aluminum‐based Metal‐Organic Framework as Water‐tolerant Lewis Acid Catalyst for Selective Dihydroxyacetone Isomerization to Lactic Acid

“…Zeolites have high catalytic activity for the dihydroxyacetone isomerization and high lactic acid yield (entries 2–8) [14,46,48] . Sn‐containing solid catalysts showed high lactic acid selectivity (>90 %) with complete dihydroxyacetone conversion (entries 3, 9) [49–50] . However, the synthesis of Sn‐containing solid catalysts is complex and requires long crystallization times [51] .…”

One-pot conversion of dihydroxyacetone into ethyl lactate by Zr-based catalysts

“…Meanwhile, Holm et al 11 found that Sn-beta zeolite which contained Lewis acid sites could produce ML from mono-and disaccharides. Inspired by these ndings, numerous Lewis acid-containing solid materials have been synthesized and used for the preparation of ALs, such as Sn-MCM-41, 12 Sn-MWW, 13 Sn-Mont, 14 SnPO, 15,16 ZrO 2 -TiO 2 , 17 Zr-SBA-15, 18 ZIFs, 19 montmorillonite-supported Pt(II) diphosphane complex 20 and NiO. 21,22 The reported catalysts containing single Lewis acid or base site are responsible for the efficient conversion of dihydroxyacetone (DHA) to lactic acid and its esters.…”