Catalysis in C1 chemistry: Future and prospect

This work summarizes the most relevant facets of the current knowledge of the principal catalytic processes involved in one carbon-atom conversions. Without doubt, natural gas (or methane) chemical conversion into high molecular weight hydrocarbons via oxidative coupling (OCM) or partial oxidation into C₁ oxygenates (POM) currently represents a great chemical and technological challenge for petrochemistry. Although the catalyst systems and the basic principles of the two types of processes are well known, a greater effort is needed towards the development of more efficient and stable catalysts under the severe operation conditions imposed by the reaction itself, as well as the need for suitable reaction design to minimize the extent of the homogeneous reaction. The alternative process is to obtain synthesis gas (CO/H₂) in a first step through steam reforming followed by a second Fischer-Tropsch hydrogenation step. However, the unfavorable energetic balance of the reforming step and the absence of selective catalysts in the latter to obtain a narrow molecular weight distribution currently leads to compromise in solutions. Among these, the high molecular weight alcohol synthesis and the recently developed Shell middle distillate synthesis (SMDS) appear to be very attractive. Of no less importance are the reactions which incorporate a CO molecule into alcohols or olefins via carbonylations and hydroformylations. Within this framework, the use of organometallic complexes anchored to functionalized polymeric matrices initiated a very intense research activity, particularly in the development of stable catalysts.