Strontium pyrophosphate modified by phosphoric acid for the dehydration of lactic acid to acrylic acid

Abstract

The dehydration of lactic acid to acrylic acid over strontium catalysts was investigated. Strontium catalysts were prepared by a precipitation method. The catalysts were calcined at 500 C for 6 hours in an air atmosphere and characterized by SEM for morphological features, by XRD for crystal phases, by FTIR for structure, by N 2 sorption for specific surface area, and by the Hammett indicator method for acidity. As for bare strontium catalysts, the types of anions have significant effects on the activity due to the acidity difference of corresponding strontium salts. Among the tested anions, the pyrophosphate anion displayed an excellent catalytic performance. Adjusting the impregnated involatile acid concentration and immersion time can change the acidity of the catalysts, resulting in a higher catalytic activity. The dehydration of lactic acid is sensitive to the surface acidity of the catalysts. Moderate acidity of the catalysts can efficiently catalyze the dehydration of lactic acid to acrylic acid. Under the optimal reaction conditions, 100% lactic acid conversion and 72.2% selectivity to acrylic acid were achieved over the phosphoric acid impregnated strontium pyrophosphate catalyst.

Selectivity Control in the Catalytic Dehydration of Methyl Lactate: The Effect of Pyridine

“…Lewis acid sites are known to be able to catalyze dehydration reactions. [20][21][22][23][24][25][26][27][28]41 Moreover, Na + in NaY has been shown 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 25 to be active in the dehyration of IPA, which is a useful surrogate molecule for ML because both have a secondary hydroxyl group and IPA cannot generate Brønsted acid sites on NaY via ionexchange. 41 To further explore the hypothesis that Lewis acid sites are the active sites for ML dehydration, IPA dehydration is used as a model reaction.…”

Production of propionic acid via hydrodeoxygenation of lactic acid over FexOy catalysts

“…[1][2][3][4] Its production mainly relies on the oxidization of propanal obtained from ethylene via hydroformylation. Lactic acid (LA) as sustainable feedstock is widely used to synthesize various chemicals such as acrylic acid, [19][20][21][22][23][24] acetaldehyde, 25-27 2,3pentanedione 28,29 and polylactic acid. However theses processes for propionic acid production are mostly based on raw materials derived from petroleum, which will become scarcer and more expensive with the rapid development of chemical industries in the long term.…”

“…41 The reaction mechanism was thought to contain two steps: (1) dehydration of LA into acrylic acid; and (2) hydrogenation of acrylic acid into propionic acid. Among these solid catalysts are sulfates, 42,43 phosphates, 22,23,28,29 alkali or alkali earth metal-modied zeolites, 19,44 mesoporous carbon, 45 metal oxides, 25,26,46 and supported platinum. Korstanje et al 4 subsequently reported that non-noble metal complexes based on molybdenum were also used to catalyze the deoxygenation of LA into propionic acid, achieving 41% yield of sodium propionate.…”

Highly efficient and robust Mg0.388Al2.408O4 catalyst for gas-phase decarbonylation of lactic acid to acetaldehyde

“…(4) and (5 [18,[52][53][54]. In this section, effect of preparation parameters such as pH values, calcination temperatures and Mg/Al molar ratios on the specific surface, pore volume and pore distribution of the catalysts was investigated with nitrogen adsorption-desorption at 77 K using Autosorb IQ instrument, and the results were depicted in Tables 1-3 and Figs.…”

“…LHSV is generally used to evaluate the performance of heterogeneous catalyst [53,57,58]. Table 9 shows the influence of LA LHSV on reaction performance.…”