Partial Oxidative and Catalytic Biomass Gasification in Supercritical Water:  A Promising Flow Reactor System

Abstract

We have developed a flow reactor system that smoothly gasifies glucose and glucose-lignin mixture solution at 673 K, 25.7 MPa. The reactor system consists of three continuous reactors, which are a pyrolysis reactor, an oxidation reactor, and a catalytic reactor. We have investigated the reactions that occurred in each reactor and evaluated favorable residence time. We have succeeded in achieving high gasification efficiency based on carbon up to 96% at 673 K, 25.7 MPa with total residence time of about 1 min. The main gaseous products were H 2 and CO 2 . The results indicated that this three-reactor system is promising for low-temperature (i.e., around 673 K) biomass gasification in supercritical water.

Towards Quantitative Catalytic Lignin Depolymerization

“…The different lignin monomer units (p-coumaryl, coniferyl, and sinapyl alcohols) as well as the multiplicity of bond types, illustrate its heterogeneity. [1][2][3] Three general routes for lignin conversion exist: 1) conversion to synthesis gas, [4][5] 2) production of bio oil through pyrolysis or liquefaction, [6][7] and 3) hydrolysis to produce monomer and/or oligomer units. [8][9] The first two routes demand severe conditions, whereas hydrolysis is comparatively mild.…”

“…Boric acid is known to form esters B(OR) 3 with alcohols in neutral and borate esters NaB(OR) 4 in basic aqueous solutions, and thus it was expected that phenolic compounds would form the corresponding esters. In addition to blocking reactions of phenols, boric acid can also act as catalyst for the acidic ether hydrolysis.…”

“…This also holds for pH values higher than 12. In this case boric acid exists as borate B(OH) 4 À and can likewise act as a capping agent to hinder condensation and addition reactions. At pH values in the range of 4-12, however, polyborates exist predominantly www.chemeurj.org in solution, and are less prone to react with phenolic and catecholic compounds.…”

EXAFS Study on Structural Change of Charcoal-supported Ruthenium Catalysts during Lignin Gasification in Supercritical Water

“…The gasification of lignin is needed for its efficient use as a high quality energy source for fuel cell or as liquid fuel by Fisher-Tropsch reaction. Supercritical water (T c = 647.3 K, P c = 22.1 MPa) gasification is a promising technique to reduce the lignin gasification temperature [2][3][4]. We have reported that lignin was converted to alkylphenol and formaldehyde via hydrolysis in supercritical water and then alkylphenol and formaldehyde decomposed to gaseous products over metal catalysts [5][6][7][8][9].…”

Oxidative Hydrolysis of Cellobiose to Glucose

“…H 2 ), and to chemicals include gasification [9], pyrolysis [10], ionic liquid catalysis [11], and hydrogenolysis over precious metal catalysts [12][13][14][15][16]. While these results are encouraging, the process requires costly hydrogen as a feed gas and, in some cases, suffers from low selectivity.…”