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A biotechnology process for
producing methanol deriving solely from plant as proffered
contributes significantly to the conversion to use of renewable
resources for the production of industrial chemicals, limits the
application of the extended definition of the term Green to qualify
a
methanol chemistry as Green, and eliminates the need for the
confirmation of the suggested methanol chemistry, on the basis that
the process of producing the methanol does not draw energy from any
energy source based on any of the
fossil
fuels. The issue of developing a biotechnology process for
producing methanol from plant is readily accomplished by developing
upon known methods of producing methanol from plants. In this regard
a known method is the production of methanol from pectin; and this
then is the basis for developing the biotechnology.
The production of truly
green methanol would also enable the production of a truly
bio-diesel fuel from vegetable oil. Currently, methanol produced
from fossil fuels is used in the production of
vegetable oil based fuel, loosely characterized as "bio-diesel",
and as such the "bio-prefix qualification of the fuel may not be
entirely justified. Indeed, for the term bio-diesel to be fully
applicable, the methanol and all the critical components and or
reactants must be produced by biotechnology process or processes.
Pectin, Chemical Structure and
Reaction
Pectin is a naturally
occurring component of plants, and is found in just about every part
of a plant. However, there are several isomers of the compound, as
the
compounds vary by the part of the plant where it occurs. In
general, pectin is the chemical that gives the
rigidity of plants to plants, including fruits. The main
raw-materials for pectin production are dried citrus peel or apple
pomace, both by-products of juice production.
Pectin is a long chain of
pectic acid and pectinic acid molecules, and because these acids are
sugars, pectin is a polysaccharide.
When fruits ripen,
the enzymes,
pectinase and pectin esterase, decompose the pectin compounds in
the fruit walls, the results of the decomposition vary: In pectin
with methyl esters, the
esters are hydrolysed into methanol, responsible for the
naturally occurring methanol in fruits juices. This process of
hydrolysis of the methyl esters or high methoxy content which
effectively removes the methoxy units from the original pectin
molecule is also known as the demethoxylation of the pectin. The
demethoxylation reaction can also be induced chemically, by the mixing of pectin esterase with
pectin. However, such chemically induced
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demethoxylation tend to
occur randomly and never completely and as such had to be performed
repeatedly in order to strip off all the methoxy units.
Biotechnology Methanol Process
Development
The bioprocess driven
production of methanol from plants essentially becomes the use of
the enzymes pectin esterase, either directly on or in a microbe to ferment a choice pectin compound. The direct use of the enzymes for
the demethoxylation of pectin simply entails the adoption of an
enzymatic reactor and the design of a biotechnology process around
such bioreactor.
The pectin esterase enzyme though present in plants
are also found in some
bacteria and fungi. These microbes therefore also provide good
sources for the fermentation of pectin into methanol, even if with
some recombinant biochemical facilitation.
Of course, as soon as an
appropriate microbe has been found, then any of the bioreactors:
biofilm bioreactors,
packed-bed bioreactor,
heterogeneous bioreactor can be use with the microbes
immobilized inside beads. This reactor design also applies to the
enzymatic bioreactor, given that the microbes immobilization
techniques adopted in the reference bioreactors followed the
standards for enzymes immobilization, and so explicit reference is
not made to the enzyme reactor any longer.
The overall biotechnology
process effectively consists, at a minimum, of the following
equipment:
Raw material storage tank
Industrial shredder unit
Pectin Extractor Vat
Filtration Vessel
Methanol Bioreactor
Flash Distillation unit
Operationally, the raw material feeds such as dried citrus
peel or apple pomace, both by-products having being acquired from
fruit juice production companies, in the Storage Bin, is fed into
the Shredder which that shreds the peels into fine grain mash, which
is then fed into the Extractor Vat. The pectin in mash is
extracted by one of two approaches, entailing either the adding of
hot
dilute acid at pH-values from 1.5 – 3.5, or adding of
3 M Sodium Chloride solution at pH 7, and stirring
for several hours during when the protopectin loses some of
its branching and chain-length and dissolves. The solution of
the peel remnants and the pectin are pumped into the Filtration
Vessel where the solid pieces are filtered off; and the extract
pumped into the Methanol Bioreactor. At the end of the reaction time
the reaction mixture now consisting of methanol and lower molecular
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pectins are pumped into the Flash Distillation Unit where the
methanol rapidly vaporizes and is distilled off; the bottom are
subsequently sold to gel producers.
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