Methane syngas production

Much recent research (7-5) has been devoted to converting methane to products that are more easily transported and more valuable. Such more valuable products include higher hydrocarbons and the partial oxidation products of methane which are formed by either direct routes such as oxidative coupling reactions or indirect methods via synthesis gas as an intermediate. The topic of syngas formation by oxidation of CH4 has been considered primarily from an engineering perspective (7-5). Most fundamental studies of the direct oxidation of CH4 have dealt with the CH4 + O2 reaction system in excess O2 and at lower temperatures (6-10). 

The higher hydrocarbon formation from syngas has long been industrialized as the Fischer-Tropsch synthesis [27]. Yet, syngas production from the C02 reforming of methane is an endothermic reaction, and requires a high temperature (ca. 1073 K) for a favorable equilibrium ... 

Jun-Mei Wei, Bo-Qing Xu et al., Highly active and stable Ni/ZrOj catalyst for syngas production by CO reforming of methane, Appl. Catal. 196(2000) pp.167-172. 

The temperature increases at the higher feed rates, even when a decrease in methane conversion occurs. The temperature is nearly constant, around 515°C at the lower feed rates, but increases to 680°C at 1080 cc/min. This is because, although methane conversion is decreasing, overall syngas production is increasing due to the larger total flow rate. 

Syngas production - steam methane reforming, SMR Steam and natural gas are reacted at high temperature (800-1000°C) and moderate pressure (20-30 bar) over a nickel catalyst supported on alumina to give Reaction sequence (2.5) ... 

The catalytic partial oxidation (CPO) of methane is an interesting alternative to to the well-established steam reforming (SRM) process for syngas production in small-scale units. However, due to the severe reaction conditions (T = 800-950°C, contact times of few ms) in CPO processes, stable and active catalysts are still required. Several catalytie systems have been used in this process, such as noble metal-based catalysts, metal-based catalysts, metal oxide catalysts and perovskites [1]. In particular, catalysts obtained by the calcination of hydrotalcite-like compounds (HTlcs) have been widely used in the CPO of methane, as they can be easily and cheaply synthesized, with a highly-dispersed... 

SrCoo 5FeOt showed a remarkable structural stability at high temperature and with different oxygen partial pressure. The conversion of methane using this tube was >98%, the selectivity to CO was 90%, and the H2/CO ratio was around 2.0. Some of these reactor tubes have been tested for syngas production up to 1000h. 

The steam to carbon ratio (S/C ratio) is the ratio of the moles of steam to atoms of carbon in the reformer feed. The S/C ratio, in conjunction with temperature and pressure, affects hydrogen yield, H2/CO ratio of the syngas product and methane conversion. The minimum S/C ratio for methane is about 1.7. However, excess steam is required to prevent carbon formation, avoid catalyst deactivation and adjust product Hj/CO [31. As a result, actual S/C ratios for steam reforming of methane are typically between 3.5 and 5.0. 

Synthesis gas produced from steam methane reforming has a H2/CO ratio of approximately 6 1, much higher than required for most applications. Table 2 [4] shows the H2/CO ratios required for major syngas-derived petrochemicals. From Table 2, the required H2/CO ratio is typically between 0 and 2. To produce lower H2/CO ratios, hydrogen can either be separated from the syngas product or CO2 can be recycled to the reformer. 

Recycling of all the CO2 in the syngas product from methane will yield a syngas with a H2/CO ratio close to the stoiciometric ratio of 3 1. To obtain lower ratios, supplemental CO2 is required. Imported CO2 is often used for syngas in the production of methanol and 0x0 alcohols. It is technically feasible to add supplemental CO2 to the reformer feed so that the final syngas product H2/CO ratio approaches 2 1 (this is described in more detail in Section III.C). However, obtaining ratios below 2 1 presents technical limitations and economic penalties. 

Syngas Production by Partial Oxidation of Methane In Different Non-Equilibrium Plasma Discharges, Application of Gliding Arc Stabilized in Reverse Vortex (Tornado) Flow... 

Non-Equilibrium Plasma-Catalytic Syngas Production from Mixtures of Methane with Water Vapor... 

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