MgAl-LDH/LDO-Catalyzed Hydrothermal Deoxygenation of Microalgae for Low-Oxygen Biofuel Production

Abstract

High oxygen content of microalgae-derived bio-oil limits their direct use in modern motors. In this study, instead of noble metal-catalyzed two-step hydrodeoxygenation, MgAl layered double hydroxides/oxides (MgAl-LDH/LDO) with tunable acidic and basic properties are developed for catalyzing the hydrothermal liquefaction (HTL) of microalgae to obtain bio-oil with a low oxygen content. The results show that both MgAl-LDH 3 and MgAl-LDO 3 enhance low O/C bio-oil production through catalyzing both the hydrolysis of cellular compounds and decarboxylation and decarbonylation of biocrude during HTL of microalgae. MgAl-LDH 3 with more acidic sites is more effective at catalyzing the hydrolysis of cellular compounds than MgAl-LDO 3 according to the relative increases of 12.98% and 9.72% of biocrude yields, respectively. However, MgAl-LDO 3 with more basic sites is more efficient in catalyzing the decarboxylation and decarbonylation and amidation of fatty acids to form hydrocarbons, esters, alcohols, and amides, which contributes to a 22.6% decrease of O/C and 28.4% increase of N/C in the bio-oil product, respectively. This work reveals that MgAl-LDH x and MgAl-LDO x are efficient at catalyzing not only the hydrolysis of cellular compounds but also the deoxidation of the reaction intermediates to produce low Ocontaining bio-oil, which might pave the way for its direct use in modern motors.

Evolution Process of Ferroan Brucite under Humid Conditions with CO2 and O2

“…For Mg 0.8 Fe 0.2 (OH) 2 and Mg 0.7 Fe 0.3 (OH) 2 , the lattice Fe 2+ content almost reached 20 and 30%, respectively, and the molar ratio of Mg 2+ /Fe 2+ was nearly to 4:1 and 2:1. The ratio was most consistent to the ratio region of divalent metal ions and trivalent metal ions for LDH formation . Hence, after oxidization of Fe 2+ to Fe 3+ , MgFe–CO 3 2– -LDHs were produced and no or less MgCO 3 ·3H 2 O were generated.…”

Competition of Dual Roles of Ionic Liquids during In Situ Transesterification of Wet Algae

“…The temperature of the column was held at 50 °C initially and then heated to 200 °C at a rate of 30 °C/min. It was finally raised up to 300 °C at a rate of 10 °C/min . The compositions of FAMEs were quantified by comparing their peak areas to the peak area of C13:0 according to the following equation: in which ∑ A is the total peak area of fatty acid esters, A EI is the peak area of the internal standard (C13:0), C EI (mg/mL) is the concentration of the internal standard, V EI is the volume of the solution of the internal standard, and W is the weight of the samples.…”

“…It was finally raised up to 300 °C at a rate of 10 °C/ min. 34 The compositions of FAMEs were quantified by comparing their peak areas to the peak area of C13:0 according to the following equation:…”

Insight into the Recent Advances in Sustainable Biodiesel Production by Catalytic Conversion of Vegetable Oils: Current Trends, Challenges, and Prospects

“…Representative structure of LDH and its roles in the transesterification of triglycerides. This figure was reproduced with permission from ref . Copyright 2021 American Chemical Society.…”