Porous Silicon-Based Catalysts for the Dehydration of Glycerol to High Value-Added Products

Abstract

Increasing worldwide biodiesel production has led to the generation of an important glycerol surplus, which needs to be valorized in order to improve the economic and environmental sustainability of the biodiesel industry. In this context, glycerol dehydration to acrolein by acid catalysis appears to be a potential route of glycerol valorization, since acrolein is an important intermediate for many chemical industries. The main drawback of this catalytic process is catalyst deactivation. Different alternatives have been proposed for overcoming it, such as the use of mesoporous materials in order to facilitate the diffusion of glycerol and reaction products, thus minimizing deactivation. This review compiles the main achievements of the use of mesoporous silica-containing materials that have been deployed either as a catalyst or for support in glycerol dehydration to acrolein. Thus, the effect of mesoporosity on both catalytic performance and deactivation will be discussed, as well as the blocking of pores by coke deposition.

Studi Literatur Pengaruh Jenis Katalis Dan Suhu Reaksi Terhadap Proses Pirolisis Gliserol Menjadi Akrolein

“…Proses fase gas lebih unggul disebabkan oleh sifat heteropolyacids dengan keasaman Brönsted yang kuat menunjukkan aktivitas katalitik awal yang baik , dehidrasi fase gas gliserol memiliki kondisi reaksi ringan [12]. Dehidrasi gliserol membutuhkan asam kondisi, karena protonasi gliserol menyebabkan penurunan penghalang energi aktivasi dari sekitar 60 hingga 20 KJ mol -1 [13]. Katalis padat memiliki aktivitas dan stabilitas yang dapat diterima ketika air berperan sebagai reaktan atau produk [14].…”

Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

“…Acrolein is the target product of glycerol dehydration. Although most authors (e.g., [4,5] review papers) have indicated that Brønsted acid sites are responsible for the reaction pathway leading to acrolein formation via 3-hydroxypropanal intermediate product, whereas Lewis acid sites activate dehydration of glycerol to hydroxyacetone, one has to take into account that LAS can be transformed to pseudo-Brønsted acid sites in the presence of H 2 O in the reaction medium [35]. Therefore, in the analysis of activity and selectivity in glycerol dehydration, both BAS and LAS should be taken into account.…”

“…For many years, various research groups have been working on different catalytic transformations of glycerol to desired target products [1][2][3]. One of the possible catalytic routes for glycerol transformation is its dehydration to acrolein [4] and oxidehydration to acrylic acid [5]. Acrolein is a versatile intermediate that is largely employed in the chemical industry, among others, for the production of acrylic acid.…”

“…Recently, the authors of two review papers [4,5] have discussed literature data on dehydration and oxidehydration of glycerol on different solid catalysts and indicated two different mechanisms of glycerol dehydration on Lewis and Brønsted acid sites (LAS and BAS, respectively). On strong Lewis acid sites, glycerol is chemisorbed with terminal OH group to form an intermediate enol (2-propene-1,2-diol) which easily tautomerizes to hydroxyacetone.…”

“…However, the catalysts containing exclusively BAS are not easily obtained. Usually BAS coexist with LAS and to achieve satisfactory glycerol dehydration selectivity to acrolein a high BAS/LAS ratio on the catalyst surface is recommended [4,5]. However, strong BAS lead to coke formation and in this way cause deactivation of the catalyst.…”