based materials such as copper chromite reported to function as catalysts in the hydrogenolysis of
methyl formate to methanol reaction 3.3. Therefore, employing a mixture of both catalysts,
methanol can be produced in a single reactor from H
2
and CO according to the above sequence of reactions [190 195]. Ohyama [196] reported
excellent activities of copper chromite catalyst for the production of methanol in liquid phase in
presence of potassium methoxide, which involves carbonylation of methanol to methyl formate and
consecutive hydrogenation of methyl formate to methanol. The effects of reaction variables on the
catalytic performance are investigated under the conditions of 373 423K temperature and 1.5
5.0Mpa pressure. Huang and Wainwright [145] observed significant improvements to the activity
of skeletal copper catalysts for the methanol synthesis achieved by adding small amounts of
Cr
2
O
3
to the surface of copper. Slurry phase concurrent synthesis of methanol has also been
described by Palekar [192] using a potassium methoxidecopper chromite mixed catalyst which
operates under relatively mild conditions 100 180
C, 30 65 atm.
2.3.2 Fast pyrolysis of biomass
Biomass, a form of renewable sources, can be transformed via thermochemical processing such
as fast pyrolysis into liquid bio oil, which is a storable and transportable fuel as well as a
potential source of a number of valuable chemicals that offer the attraction of much higher added
value than fuels. Bio oil is successfully used as boiler fuel and also showed promise in diesel
engine and gas turbine applications. Upgrading bio
oil to a quality of transport liquid fuel still poses several technical challenges and is not currently
economically attractive. Some chemicals, especially those produced from the whole bio oil or its major
fractions offer
more interesting commercial
opportunities. The
main properties
and applications of bio oil have been reviewed by
Czernik and Bridgwater [197]. Bio oils are complex hydrocarbon mixtures
known to contain significant amount of oxygenated compounds including lignin derivates which
ultimately lead to low heating values, low stabilities, high viscosity, low volatility and low
pH. Therefore, in order to improve the quality of the bio oils in terms of heating values, viscosity
and storage stability, the oxygenates and the large molecules derived from lignin need to be reformed
into more useful products. Catalytic pyrolysis is a promising approach for upgrading bio oil involves
direct catalytic conversion in the vapour phase at low pressure via vapour cracking and reforming.
Incorporating a catalyst into the pyrolysis unit is expected to enhance deoxygenation, cracking and
reforming reactions. The selection of appropriate catalysts plays a vital part in bio oil upgrading.
The severity of these catalytic reactions often influences the liquid product distribution and
depends largely on types of catalyst and other processing parameters. Pattiya et al. [198] used
copper chromite catalyst for cassava rhizome as the biomass feedstock for upgrading bio oil. They
observed that the copper chromite was selective to the
reduction of
most oxygenated
lignin derivatives.
2.3.3 Preferential oxidation of CO
