Page 204 - Advances in bioenergy (2016)

industry, as found in the wastewater to be utilized for H generation. In APR, water gas shift
2
reaction is favored by the availability of controlled pressure (5–50 bar) and desired
temperature, which drives the outcome with lower amounts of CO and higher yield of

hydrogen. APR has several advantages over the existing methods to produce H via the steam
2
reforming of hydrocarbons.

Comparative energy consumption in heating and vaporising both water and oxygenated
hydrocarbon is less in APR than in SR.

Most raw materials used for APR are nonflammable and nontoxic, providing a safe
operational platform for storage and handling. Glycerol, ethanol, acetic acid of low grade
purity can be used as feedstock.

Availability of adequate pressure in the process makes it possible to purify hydrogen by
implementation of pressure-swing adsorption or membrane technologies and to separate
the CO for either sequestration or to be used as a chemical entity for industry.
2
Undesirable decomposition reactions are minimized during APR process as it occurs with
hydrocarbons at elevated temperatures leading to char and tar formation.

Multistage reactor configuration can be eliminated in APR, as APR is appropriate in single
stage and low temperature profile (<300°C) and the purified H can be obtained by using
2
well-known pressure-swing adsorption technology.

On the same line among different precious metal catalysts tested, the activity of the different
metals for H production was in the following descending order: Pt > Ru > Pd > Ni, and
2
alumina support is most unfavourable for APR, whereas precious metal catalysts over carbon
and activated carbon exhibited significantly better activity than alumina. As discussed by
Meryemoglu et al., the solubilized lignocellulosic biomass of wheat straw in subcritical water
and aqueous-phase reforming of solubilized organic materials in the presence of various types
of reforming catalysts follows the descending order, Raney-Ni > Pt > Ru > Pd > Ni, for the
68
production of H rich gas mixture. But Raney-nickel catalysts showed good performance on
2-
degradation of organic compounds solubilized from lignin fraction during APR process. As
discussed by Davda et al., the catalysts based on Pt and Ni–Sn alloys are promising materials

for hydrogen production by APR. 69

For analysis of APR process, focus on its thermodynamic and kinetics considerations is
required, whereas different factors such as nature of catalyst, nature of feed, reaction
conditions, and its pathways are most influential for APR of any oxygenated compound during
its reforming process. Optimum reaction parameters and yields as determined by a
thermodynamic study of autothermal reforming of some model bio-oil compounds are depicted
in Table 8.6. When oxygen reacts with oxygenated compounds such as glycerol and phenol to
produce energy, it is in situ transferred to dry reforming process. Dry autothermal reforming
(DATR) is a better process than dry reforming (DR), as in DR the external energy is necessary
to carry out the process and more carbon is formed in the reactor while DATR does not require
external energy and minimum carbon is formed at optimized conditions. Kale and Kulkarni