Canada is blessed with vast reserves of natural gas. A large portion of the reserves is in the frontiers and remains unexploited due to the prohibitive cost of transporting the low energy density gas. Moreover, only a small portion of Canada's consumption of natural gas is used as a chemical feedstock. Current conversion technologies involve an initial steam reforming step to produce synthesis gas which is then converted to methanol, gasoline or other products. These indirect routes are energy intensive and costly. Enormous market opportunities can be created especially for remote natural gas by developing new direct conversion technologies.
The development of direct conversion routes is at an early stage. Oxidative coupling of methane to ethylene and partial oxidation to methanol are the two routes most investigated. Engineering and economic evaluations indicate, for both routes, that the product selectivities are less than desirable due to the deep oxidation of the reaction intermediates or products to form carbon oxides.
Aggressive R and D is needed in catalyst design, reactor design and process design to overcome these chemical and engineering challenges and speed the development of direct conversion routes to commercial viability.
Natural gas discovered recoverable reserves in Canada were estimated at 186 EJ (extajoules) of which 71.2 EJ are conventional (Table 1). The ultimate recoverable resource potential is estimated at 560 EJ. Unfortunately, 55% of Canada's reserves are in the frontier regions with no pipeline service. These estimates exclude tight gas reserves and coal bed methane. Canada exports about 43% of its annual production of natural gas to the U.S. Of the domestic demand, only 8% is used as a chemical feedstock (TABLE 2). The limited exploitation of natural gas as a chemical feedstock, despite its abundance in Canada, is mainly due to the lack of viable conversion technologies.
This paper discusses the need to accelerate R and D in Canada in order to develop technologies for converting this abundant commodity to value-added easily transportable liquid fuels, fuel additives and petrochemicals. Available indirect commercial processes are discussed briefly. This is followed by a discussion of the known direct routes. The technical challenges and the economic requirements for making these routes commercially viable are also discussed. The paper concludes by recommending R and D areas to speed the development of these technologies.
The indirect routes involve two steps: the production of synthesis gas from natural gas via steam reforming over Ni-based catalysts at temperatures higher than 800C
CH4 + H2O = 3H2 + CO