Production of gaseous and liquid chemicals by aqueous phase reforming of crude glycerol: Influence of operating conditions on the process

Abstract

The present work studies the influence of the temperature (200-240 ºC), pressure 12 (38-50 bar), glycerol concentration (10-50 wt.%) and mass of catalyst/ glycerol mass 13 flow rate ratio (W/m glycerol = 10-40 g catalyst min/g glycerol) during the aqueous 14 phase reforming (APR) of a glycerol solution obtained from the production of 15 biodiesel. The operating conditions exerted a statistically significant influence on the 16 reforming results. Specifically, the global glycerol conversion and the carbon 17 converted into gas and liquid products varied as follows: 4-100%, 1-80% and 16-18 93%, respectively. The gas phase was made up of H 2 (8-55 vol.%), CO 2 (34-66 19 vol.%), CO (0-4 vol.%) and CH 4 (6-45 vol.%). The liquid phase consisted of a 20 mixture of alcohols (monohydric: methanol and ethanol; and polyhydric: 1,2-21 propanediol, 1,2-ethanediol, 2,3-butanediol), aldehydes (acetaldehyde), ketones (C3-22 ketones: acetone and 2-propanone-1-hydroxy; C4-ketones: 2-butanone-3-hydroxy 23 and 2-butanone-1-hydroxy; and cyclic ketones), carboxylic acids (acetic and 24 propionic acids) and esters (1,2,3-propanetriol-monoacetate), together with unreacted glycerol and water. The relative amount (free of water and un-reacted glycerol) of 1 these compounds in the liquid phase was as follows: monohydric alcohols: 4-47%, 2 polyhydric-alcohols: 14-68%, aldehydes: 0-5%, C3-ketones: 2-33%, C4-ketones: 0-3 10 %, ciclo-ketones: 0-6%, carboxylic acids: 2-43%, and esters: 0-46%. This process 4 turned out to be highly customisable for the valorisation of crude glycerol for the 5 production of either gaseous or liquid products. Gas production is favoured at a low 6 pressure (39 bar), high temperature (238 ºC), high W/m glycerol ratio (38 g catalyst 7 min/g glycerol) and employing a 15 wt.% glycerol solution. A high pressure (45 bar), 8 medium temperature (216 ºC), medium W/m glycerol ratio (22 g catalyst min/g 9 glycerol) and the feeding of a 16 wt.% glycerol solution favours the production of 10 liquid products.

A review of catalytic aqueous-phase reforming of oxygenated hydrocarbons derived from biorefinery water fractions

“…The carbon concentration in the liquid products decreased at higher temperatures [75] due to the promotion of CeC and CeO bond cleavage [41]. Additionally, hydrogen yield is favoured at high temperature and low pressure [72,76].…”

Cheese whey management by catalytic steam reforming and aqueous phase reforming

“…This catalyst has a 28% (relative atomic percentage) Ni expressed as Ni/(Ni+Co+Al+Mg), an atomic Mg/Al ratio of 0.26 and an atomic Co/Ni ratio of 0.10, with a BET surface area of about 132 m 2 /g [41]. A Ni-La/Al, having a 28% (relative atomic percentage) of Ni expressed as Ni/(Ni+Al+La), an atomic La/Al ratio of 0.035 and a BET surface area of 187 m 2 /g was used for the aqueous phase reforming experiments [42].…”

Thermodynamic Analysis of Autothermal Reforming of Synthetic Crude Glycerol (SCG) for Hydrogen Production

“…The influence of the steam to feed ratio on hydrogen production rate have been reported in the literature for several catalytic systems in the glycerol reforming, therefore SCG ratio is a key parameter in determining the amount of hydrogen produced within the reaction conditions envelope [22]. Figure 5 shows the impact of S/SCG ratio on the molar composition and flowrate of hydrogen at temperature of 973 K and O/G ratio of 0.125.…”

“…Increasing the ChemEngineering 2017, 1, 4 7 of 16 [22]. Figure 5 shows the impact of S/SCG ratio on the molar composition and flowrate of hydrogen at temperature of 973 K and O/G ratio of 0.125.…”

“…Therefore, a trade-off between the cost of steam and the purity of the product gas stream is required to establish the optimum S/SCG ratio. [22]. Figure 5 shows the impact of S/SCG ratio on the molar composition and flowrate of hydrogen at temperature of 973 K and O/G ratio of 0.125.…”