Ikelic - Alliance Digital Repository

NATURAL GAS
conventional process. On the other hand,
methanol synthesis via MF showed a STY of
0.13 kilograms per liter per hour at 423 K and
5 MPa (feed: H2/CO =1), which is only one-fifth
of the STY in the ICI process. However, the STY
is expected to be improved by optimizing reac
tion conditions and catalyst concentration in the
liquid phase, and by searching for a more active
catalyst system.
Ohyama points out, however, that questions on
extension and stability of the catalyst life are im
portant subjects in the BNL process.
####
SULFUR PROCESSING PROVIDES NEW
ROUTE FOR NATURAL GAS TO GASOLINE
The Institute of Gas Technology (IGT) has been
working
on a new synthesis route for natural gas
to gasoline. The IGT approach, as described by
E. Erekson and F. Miao at a Symposium on Alter
native Routes for the Production of Fuels, con
sists of two steps that each utilize catalysts and
sulfur containing intermediates:
- Convert
- Convert
natural gas to CS2
to CS2 liquid hydrocarbons
The general equations for the two steps are:
CH4
+ 2 H S =
CS,
+ 4 H_
CS2 + 3H2=[-CH2-f+2H2S
The H2S is recycled, and the overall process is a
net hydrogen producer.
A catalyst is being developed at IGT for the first
step. The second step has been patented by
Mobil.
Sulfur, which has been considered as a poison, is
used as a reactant in the proposed process. This
method of methane conversion utilizes HS to
catalytically convert methane to CS2. Then CS2
plus hydrogen can be catalytically converted to
gasoline range hydrocarbons. All of the HS gen-
5-7
erated during the to gasoline reaction is
CS2
recycled. This process does not require steam
reforming
nor the manufacture of hydrogen.
IGT is studying the process as part of a 3-year
laboratory-scale research project sponsored, in
part, by the United States Department of Energy.
IGT has already found a catalyst for the first step
that is active above 900C at 1 atm and achieves
better than 90 percent conversion of methane.
The researchers now plan to carry out
laboratory-scale studies to improve conversion of
carbon disulfide in the second step
tegrate the two steps into one process.
####
FULLERENES CATALYZE METHANE
and to in
CONVERSION TO HIGHER HYDROCARBONS
At SRI International, H. Wu et al. have been study
ing
the use of fullerenes and fullerene soot as
catalysts for methane conversion. A progress
report was given at the Symposium on Alterna
tive Routes for the Production of Fuels, held in
Washington, D.C. last August.
Wu et al. note that the main difficulty in convert
ing
methane is the production of undesirable side
products. Oxidative methods easily convert
methane to higher hydrocarbons, but over-
oxidation to C02 makes it an uneconomical
method. Alternatively, simple thermal decomposi
tion of methane also makes higher hydrocar
bons; but the production of liquid fuels from
methane by this method is not yet economically
feasible because of the high C-H bond strength
of methane compared with that of reaction
products. At the high temperatures required to
activate methane, the C products formed will fur
ther decompose and produce still higher
hydrocarbons, aromatics, and coke.
Direct coupling of methane can be achieved ther
mally without catalyst. The key to these pyrolysis
reactions is to generate methyl radicals, which
then polymerize into higher hydrocarbons.
However, current methods are thought to
THE SYNTHETIC FUELS REPORT, JANUARY 1995