A Review on Catalysts Development for Steam Reforming of Biodiesel Derived Glycerol; Promoters and Supports

Abstract

In the last decades, environmental crises and increasing energy demand have motivated researchers to investigate the practical techniques for the production of clean fuels through renewable energy resources. It is essential to develop technologies to utilize glycerol as a byproduct derived from biodiesel. Glycerol is known as a sustainable and clean source of energy, which can be an alternative resource for the production of value-added chemicals and hydrogen. The hydrogen production via steam reforming (SR) of glycerol using Ni-based catalysts is one of the promising approaches for the entry of the hydrogen economy. The purpose of this review paper is to highlight the recent trends in hydrogen production over Ni-based catalysts using the SR of glycerol. The intrinsic ability of Ni to disperse easily over variable supports makes it a more viable active phase for the SR catalysts. The optimal reaction conditions have been indicated as 650–900 °C, 1 bar, and 15 wt% Ni in catalysts for high glycerol conversion. In this review paper, the effects of various supports, different promoters (K, Ca, Sr, Ce, La, Cr, Fe), and process conditions on the catalytic performance have been summarized and discussed to provide a better comparison for the future works. It was found that Ce, Mg, and La have a significant effect on catalytic performance as promoters. Moreover, SR of glycerol over hydrotalcite and perovskite-based catalysts have been reviewed as they suggest high catalytic performance in SR of glycerol with improved thermal stability and coke resistance. More specifically, the Ni/LaNi0.9Cu0.1O3 synthesized using perovskite-type supports has shown high glycerol conversion and sufficient hydrogen selectivity at low temperatures. On the other hand, hydrotalcite-like catalysts have shown higher catalytic stability due to high thermal stability and low coke formation. It is vital to notice that the primary concern is developing a high-performance catalyst to utilize crude glycerol efficiently.

Stability and activity maintenance of Ni catalysts supported on La‐, Ce‐, and Mg‐promoted Al 2 O 3 and ZrO 2 for H 2 production from steam reforming of glycerol

“…Rh, Ru, Pt, and Ni, the VIII elements, are found very effective in promoting the gasification efficiency of SR due to the enhanced cleavage of C C, O H, and C H bonds of the organic feeds. 3,5 By comparison of the active metals aforementioned, Nibased catalysts show great potential for practical use owing to their comparable high activity with the noble metals and relatively low cost.…”

Recent Advances in Glycerol Catalytic Valorization: A Review

“…Glycerol carbonate from glycerol can be produced through several routes, which are commonly divided into two groups-indirect or direct routes-depending on the carbonate sources [211]; direct routes include carboxylation (CO 2 ) and oxidative carboxylation (CO + O 2 ), whilst indirect routes can be transesterification with di-carbonates or alkyl carbonates, glycerolysis-urea [212], and phosgenation. It is important to highlight the possibility to use CO 2 as a carbonate source, either because it helps with the valorization of other large by-products or presents the possibility of some mitigation and control of CO 2 emissions.…”

“…Indirect routes normally lead to a higher yield of glycerol carbonate, where the catalysts play a key role. Starting with glycerol transesterification, some reviews have summarized the types of catalysts [207,211], which are very similar to other transesterification processes, including K 2 CO 3 , CaO, MgO [213], ZnO, and H 2 SO 4 . Several types of hydrotalcite have been tested, such as Al/Mg, Al/Li, Al/Ca, Mg/Al, etc.…”

“…The production of H 2 has gained a huge amount of interest in the last decades, as it is a potential clean energy fuel [57]. In this route, there are several technologies employed, such as gasification, steam reforming [211,255], dry reforming [100,256], pyrolysis, and aqueous phase reforming [257] (see Section 3.3). The drawbacks of reforming are the drastic reaction conditions (atmospheric pressure and temperature < 800 • C) and many side reactions and the production of CO 2 .…”

Preparation and Characterization of Ni/ZrTiAlOx Catalyst via Sol-Gel and Impregnation Methods for Low Temperature Dry Reforming of Methane

“…Moreover, through the DRM, the synthesis gas ratio can be tuned for the Fischer-Tropsch processes to produce value-added chemicals such as dimethyl ether (DME) and methanol [4][5][6][7]. Ni-based catalysts have generally been reported to produce the syngas through various hydrocarbon-based feedstock [8,9]. Furthermore, Ni-based catalysts are considered to be a suitable catalyst for the reforming reaction due to the availability and abundance of Ni compared to Nobel metals.…”