Cleanup and Conversion of Biomass Liquefaction Aqueous Phase to C3–C5 Olefins over ZnxZryOz Catalyst

Abstract

The viability of using a ZnxZryOz mixed oxide catalyst for the direct production of C4 olefins from the aqueous phase derived from three different bio-oils was explored. The aqueous phases derived from (i) hydrothermal liquefaction of corn stover, (ii) fluidized bed fast pyrolysis of horse litter, and (iii) screw pyrolysis of wood pellets were evaluated as feedstocks. While exact compositions vary, the primary constituents for each feedstock are acetic acid and propionic acid. Continuous processing, based on liquid–liquid extraction, for the cleanup of the inorganic contaminants contained in the aqueous phase was also demonstrated. Complete conversion of the carboxylic acids was achieved over ZnxZryOz catalyst for all the feedstocks investigated. The main reaction products from each of the feedstocks include isobutene (>30% selectivity) and CO2 (>23% selectivity). Activity loss from coking was also observed, thereby rendering deactivation of the ZnxZryOz catalyst, however, complete recovery of catalyst activity was observed following regeneration. Finally, the presence of H2 in the feed was found to facilitate hydrogenation of intermediate acetone, thereby increasing propene production and, consequently, decreasing isobutene production.

Ethanol as a Renewable Building Block for Fuels and Chemicals

“…45,46 The production of propene has also recently been demonstrated using a Zn x Zr y O z mixed oxide system, previously reported useful for isobutene production (discussed in the following section). 47 Using H 2 as the carrier gas instead of N 2 drives the hydrogenation of intermediate acetone, which shifts the product distribution toward propene instead of isobutene. Nearly complete conversion of ethanol was achieved with a selectivity to propene of 20% (using a 20 wt % ethanol in water feedstock).…”

“…This catalyst system permits adjusting the propene/isobutene selectivity. 47 Figure 2 suggests that propene can be a potentially profitable product.…”

“…Acetone can then be hydrogenated to form isopropanol before dehydration to propene (Figure , reactions 3–5) . This chemistry has been previously explored over Sc promoted In 2 O 3 catalysts. , The production of propene has also recently been demonstrated using a Zn x Zr y O z mixed oxide system, previously reported useful for isobutene production (discussed in the following section) . Using H 2 as the carrier gas instead of N 2 drives the hydrogenation of intermediate acetone, which shifts the product distribution toward propene instead of isobutene.…”

“…Nearly complete conversion of ethanol was achieved with a selectivity to propene of 20% (using a 20 wt % ethanol in water feedstock). This catalyst system permits adjusting the propene/isobutene selectivity Figure suggests that propene can be a potentially profitable product.…”

Sustainable Catalytic Conversion of Biomass for the Production of Biofuels and Bioproducts

“…The group of Dr. Robert A. Dagle analyses the viability of using a Zn x Zr y O z mixed oxide catalyst for the direct production of C4 olefins from the aqueous phase derived from three different bio-oils. Complete conversion of the carboxylic acids was achieved over said catalyst for all the feedstocks investigated, being the main reaction product isobutene (>30% selectivity) [14]. Pedro Maireles-Torres et al have contributed with a work about the selective conversion of glucose into HMF using L-type zeolites with different morphologies, where they also show that the addition of CaCl 2 has a positive influence on the catalytic performance [15].…”