Biofuels starting materials for hydrogen production
Future developments in energy-efficient processes and potential solutions for the energy-related environmental tasks are coupled with hydrogen-based technologies. Introductory parts of this chapter are focused on the specifics of H2 generation from biomass. Within the framework of this topic, three platforms are compared: conversion of simple sugars, cellulose, and thermochemical conversion of biomass to hydrogen-containing gaseous mixtures. Three approaches for generation of biofuels starting materials for hydrogen production are considered: the first one includes sugars and organic acids; the second one includes lignocellulose, woodchips, etc.; finally, the third approach considers the possible routes of biomass gasification. In all cases, the hydrogen needs to be separated (to be recovered) from the hydrogen-containing multicomponent gaseous mixtures of biogenic origin. Membrane-based gas separation processes are considered for H2 recovery from gaseous sources, including (1) estimation of commercial and lab-scale polymeric membranes for recovery of H2 from gaseous mixtures, containing additionally CO2, CO, N2, CH4, H2S, with calculation of standard membrane process itself; (2) membrane contactors for hydrogen recovery from H2/CO2 mixtures; (3) combined membrane/pressure-swing adsorption (PSA) systems for hydrogen recovery from gaseous mixtures of biogenic origin. It is shown that H2 recovery can be successfully realized as a combination of standard membrane method (H2 preconcentrating) and PSA (H2 conditioning). Potential of whole process (biomass treatment and H2 recovery as a fuel) requires the active generation of knowledge for development of the desired bioprocesses and highly selective membranes.