High Yield to 1-Propanol from Crude Glycerol Using Two Reaction Steps with Ni Catalysts

Martín N. Gatti,Nora N. Nichio,Gerardo F. Santori,Francisco Pompeo,Julieta L. Cerioni

doi:10.3390/catal10060615

Abstract

The objective of the present work is to achieve high yield to 1-propanol (1-POH) by crude glycerol hydrogenolysis in liquid phase and find an alternative to the use of noble metals by employing Ni catalysts. Two Ni catalysts with different supports, alumina (γ-Al2O3), and a phosphorous-impregnated carbon composite (CS-P) were studied and characterized in order to determine their acid properties and metallic phases. With the Ni/γ-Al2O3 catalyst, which presented small particles of metallic Ni interacting with the acid sites of the support, it was possible to obtain a complete conversion of crude glycerol with high selectivity towards 1,2-propylene glycol (1,2 PG) (87%) at 220 °C whereas with the Ni/CS-P catalyst, the presence of AlPOx species and the Ni2P metallic phase supplied acidity to the catalyst, which promoted the C-O bond cleavage reaction of the secondary carbon of 1,2 PG to obtain 1-POH with very high selectivity (71%) at 260 °C. It was found that the employment of two consecutive reaction stages (first with Ni/ γ-Al2O3 at 220 °C and then with Ni/CS-P at 260 °C) allows reaching levels of selectivity and a yield to 1-POH (79%) comparable to noble metal-based catalysts.

Highlights

Glycerol is a by-product of biodiesel synthesis and is currently considered an important biomass resource because it can be used as a raw material to synthesize other chemical compounds that, in the past, were obtained by petrochemical methods [1,2,3,4]
For the γ-Al2 O3 support, the main peaks are observed at 2θ = 18.9◦, 32.5◦, 36.9◦, 39.1◦, 45.3◦, 59.6◦ and 66.7◦ characteristic of this low crystallinity aluminum oxide ()
Since it was not possible to observe phosphorus phases on the CS-P support, this composite was analyzed by NMR spectroscopy

Summary

Introduction

Glycerol is a by-product of biodiesel synthesis and is currently considered an important biomass resource because it can be used as a raw material to synthesize other chemical compounds that, in the past, were obtained by petrochemical methods [1,2,3,4]. With respect to 1,2-PG, it has been widely used as a raw material in cosmetic, pharmaceutical, food, and chemical industries [14]. In the literature, there are more scientific contributions focused on glycerol hydrogenolysis to produce 1,2-PG than to produce 1-POH [19,20], though the latter is a high value-added product [21]

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Conclusion