Highly Selective Solid Acid Catalyst H1−xTi2(PO4)3−x(SO4)x for Non-Oxidative Dehydrogenation of Methanol and Ethanol

Abstract

Abstract:The conversion of alcohols towards aldehydes in the presence of catalysts by non-oxidative dehydrogenation requires special importance from the perspective of green chemistry. Sodium (Na) super ionic conductor (NASICON)-type hydrogen titanium phosphate sulfate (HTPS; H 1−x Ti 2 (PO 4 ) 3−x (SO 4 ) x , x = 0.5-1) catalysts were synthesized by the sol-gel method, characterized by N 2 gas sorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), NH 3 temperature-programmed desorption (NH 3 -TPD), ultraviolet-visible (UV-VIS) spectroscopy, and their catalytic properties were studied for the non-oxidative dehydrogenation of methanol and ethanol. The ethanol is more reactive than methanol, with the conversion for ethanol exceeding 95% as compared to methanol, where the conversion has a maximum value at 55%. The selectivity to formaldehyde is almost 100% in methanol conversion, while the selectivity to acetaldehyde decreases from 56% to 43% in ethanol conversion, when the reaction temperature is increased from 250 to 400 • C.

Ethanol Dehydrogenation: A Reaction Path Study by Means of Temporal Analysis of Products

“…Wang et al [53] tested Au supported on ZnZrO x at temperatures between 30 • C and 400 • C and observed that the addition of Au favors the dehydrogenation route over the dehydration path. Mitran et al [54] investigated mixtures of ethanol and methanol with their H 1−x Ti 2 (PO 4 ) 3−x (SO 4 ) x -catalyst and observed higher conversions of ethanol (> 95%) compared to those of methanol (55%).…”

Non‐Classical Conversion of Methanol to Formaldehyde

“…SO 4 2− ‐Ce 2 (MoO 4 ) 3 /SiO 2 is another Ce‐containing catalyst suggested for the dehydrogenation of CH 3 OH by Said et al 45, for which high stability and CH 2 O selectivity at relatively low temperatures (250–400 °C) were claimed. One more example of the active catalytic systems developed in the last years is a solid acid H 1–x Ti 2 (PO 4 ) 3–x (SO 4 ) x ( x = 0.5–1) suggested by Mitran et al 32.…”

“…However, at that high temperatures decomposition of CH 2 O to CO is thermodynamically favorable [17]. For instance, it was estimated that for a feed containing 2.7 mol CH 3 OH at 750 °C the equilibrium yield of CO is 10 %, whereas the CH 2 O yield is 2.0 10 -5 % [31,32]. Therefore, selective catalysts are required for the production of CH 2 O. Catalysts containing transition metals, alkali metals, oxides, zeolites or phosphates have been investigated for the non-oxidative dehydrogenation of CH 3 OH.…”

Non‐oxidative Dehydrogenation of Methanol to Formaldehyde over Bulk β‐Ga2O3

“…Among other elements, sodium-based catalysts have demonstrated high activity at high temperatures (650-900 °C). [16,17] In the last decade, Mo-containing compounds such as CaMoO 4 [18] and Ce 2 (MoO 4 ) 3 ) [19] as well as solid acids (hydrogen titanium phosphate sulfate, H 1-x Ti 2 (PO 4 ) 3-x (SO 4 ) x , x = 0.5-1) [20] have been reported as catalysts for the non-oxidative dehydrogenation of CH 3 OH. Both high catalytic activity combined with high selectivity and catalyst stability were claimed.…”