Natural gas emissions contribute to climate change, and equally importantly, affect the health of populations near gas fields.[1] At night, the flares from the Bakken fields in North Dakota burn as bright as the lights in cities as large as Minneapolis. Rather than flaring (or worse, venting), this associated natural gas represents a multi‐billion dollar opportunity.[2] Pipelines and liquefying natural gas are cost prohibitive in many cases. Converting methane to fuels is an attractive alternative. We examined three options to convert natural gas to syngas (H2 and CO), which is the first step to producing fuels: Steam Methane Reforming (SMR), Auto‐Thermal Reforming (ATR), and Catalytic Partial Oxidation (CPOX). Based on a multi‐objective optimization analysis, C5+ hydrocarbon yields are highest with CPOX as the first step followed by Fischer‐Tropsch synthesis (FT). A micro‐refinery with the CPOX‐FT process treating 2800 normalkL·d−1 (100 MCF·d−1) natural gas, produces 1300 normalL·d−1 (8.2 bbl·d−1) of C5+ hydrocarbons. Maximum yields for the SMR‐FT and ATR‐FT processes are 938 normalL·d−1 and 1100 normalL·d−1 (5.9 bbl·d−1, 7.0 bbl·d−1) of C5+, respectively. Large‐scale POX and ATR processes produce 1600 L per 2800 kL (10 bbl per 100 MCF) of natural gas.

No abstract

The effect of injection of hydrogen sulfide, an available inexpensive byproduct in Iran’s petrochemical industry, on the rate of coke formation over chromium, iron, and stainless-steel (SS) coupons in thermal cracking of ethane was investigated. In a laboratory reactor, coke formation on the metal coupons was measured in the temperature range of 1098–1148 K after a fixed time of 900 s. Nitrogen was used as an inert diluent to exclude the concomitant coke oxidation in the commonplace steam-cracking process. The role of hydrogen sulfide was examined through an additive feeding policy either as a pure presulfidation of the coupons with a 200 ppmw concentration for 20 min or via continuous introduction of 25 and 50 ppmw amounts of hydrogen sulfide into the gas feed stream. The presulfidation reduced the rates of coke formation up to 20, 45, and 30% over Cr, Fe, and SS samples, respectively. However, the continuous injection of hydrogen sulfide showed a complex behavior depending upon the temperature, so that the rate of coke formation increased by 20–120% at higher temperatures but decreased by 25–30% at lower temperatures. The complex and contradictory behaviors of the H2S effect on the coke formation for the presulfidation and the continuous sulfidation scenarios were well-described through a simplified mechanism. An empirical model was developed to predict the rate of coke formation over the selected metal samples at given operating conditions and known H2S and ethylene concentrations. The model predictions were in good agreement with the experimental results.

No abstract

No abstract