Synthesis and Regeneration of Nickel-Based Catalysts for Hydrodeoxygenation of Beech Wood Fast Pyrolysis Bio-Oil

Abstract

Four nickel-based catalysts are synthesized by wet impregnation and evaluated for the hydrotreatment/hydrodeoxygenation of beech wood fast-pyrolysis bio-oil. Parameters such as elemental analysis, pH value, and water content, as well as the heating value of the upgraded bio-oils are considered for the evaluation of the catalysts’ activity and catalyst reuse in cycles of hydrodeoxygenation after regeneration. The reduction temperature, selectivity and hydrogen consumption are distinct among them, although all catalysts tested produce upgraded bio-oils with reduced oxygen concentration, lower water content and higher energy density. Ni/SiO2, in particular, can remove more than 50% of the oxygen content and reduce the water content by more than 80%, with low coke and gas formation. The evaluation over four consecutive hydrotreatment reactions and catalyst regeneration shows a slightly reduced hydrodeoxygenation activity of Ni/SiO2, mainly due to deactivation caused by sintering and adsorption of poisoning substances, such as sulfur. Following the fourth catalyst reuse, the upgraded bio-oil shows 43% less oxygen in comparison to the feedstock and properties comparable to the upgraded bio-oil obtained with the fresh catalyst. Hence, nickel-based catalysts are promising for improving hardwood fast-pyrolysis bio-oil properties, especially monometallic nickel catalysts supported on silica.

Evaluation of High-Loaded Ni-Based Catalysts for Upgrading Fast Pyrolysis Bio-Oil

“…Propylene glycol was formed with both Ni and Ni-Cr, resulting in 0.72 g and 0.64 g, respectively, mostly concentrated in the upgraded aqueous phases. In agreement with our previous finding and other investigations, the formation of propylene glycol is attributed to the hydrogenation of acetol [13,60]. Moreover, its hydrodeoxygenation may lead to the formation of 1-propanol, a compound only identified in the upgraded fractions.…”

“…The UBWBO showed an O/C ratio of 0.19, which is much lower compared to the BWBO and to all the upgraded products obtained with all catalysts at 175 °C and 225 °C. The high hydrodeoxygenation activity of the Ni/SiO2 catalyst used in the first upgrading reaction has been previously reported elsewhere [13]. After the reaction, the O/C ratio was further reduced to 0.11 whereas the H/C ratio increased considerably from 1.38 to 1.46.…”

“…Among the products, phenol was observed in higher concentrations in the UOP Ni,225 A number of 24 compounds belonging to the guaiacol group were identified in the BWBO, with guaiacol (0.621 wt.% dry basis), 4-methyl-guaiacol (0.683 wt.% dry basis), eugenol (0.22 wt.% dry basis), cis-isoeugenol (0.32 wt.% dry basis), vanillin (0.47 wt.% dry basis), and acetoguaiacone (0.34 wt.% dry basis) among the main compounds. Eugenol and isoeugenol were hydrogenated to 4-propylguaiacol, as previously reported [13,61]. The concentration of guaiacol reduced slightly to 0.18 g with Ni and to 0.17 g with Ni-Cr.…”

Effect of Dilute Acid and Alkali Pretreatments on the Catalytic Performance of Bamboo-Derived Carbonaceous Magnetic Solid Acid

“…The depletion of fossil fuel reserves and climate change issues have raised concerns about renewable petroleum alternatives with the increment of global energy demand [1,2]. Biomass has received increasing attention in recent decades due to it being widespread, abundant, diverse, and inexpensive.…”

Regeneration of Raney®-Nickel Catalyst for the Synthesis of High-Value Amino-Ester Renewable Monomers

“…Since the discovery of Ni(CO) 4 complexes by Mond in 1888 [1], organo-nickel chemistry saw comprehensive developments. Nickel-based catalysts proved their effectiveness in several types of reactions, including cross-couplings [2], methanations [3,4], nucleophilic allylations [5,6], oligomerizations [7], hydrodeoxygenations [8], and hydrogenations [9]. This last reaction can make use of Raney ® -nickel, which is the most popular catalyst in the field.…”