Ammonia is one of the most produced chemicals, mainly synthesized from fossil fuels for fertilizer applications. Furthermore, ammonia may be one of the energy carriers of the future, when it...

The effect of the axial temperature profile upstream and downstream of catalyst bed on the performance of non‐oxidative‐coupling‐of‐methane (NOCM) over Fe/SiO2 was determined. A three‐zone oven was used with independent temperature control of the catalyst‐zone as well as the zones upstream and downstream. It was found that catalytic initiation followed by residence time at 1000 °C downstream the catalyst bed increases CH4 conversion by a factor of 8, while decreasing carbonaceous deposit selectivity from 40 to 12 C%. Residence time at 1000 °C upstream of the catalyst bed causes deposit formation on the catalyst without significantly influencing methane conversion. A shallow catalyst bed followed by significant residence time at high temperature maximizes methane conversion and minimizes coking. This work shows that axial temperature profile and residence time upstream and downstream of the catalyst bed strongly influence the performance in catalytic NOCM.

The gasification of pinewood pyrolysis oil with potassium hydroxide dissolved was investigated, using a potassium salt loaded char as catalyst, to screen if this would result in a lower tar yield in the product stream. Experiments were performed at 700 °C, after which the product stream was thoroughly condensed and the gas stream was analyzed. The results show a significant tar reduction for a fixed potassium-loaded char bed at a gas hourly space velocity (G C1 HSV) of 237 h −1 . If the G C1 HSV is reduced, the reduction in tar increases. A reduction of a factor of 10 was observed when the feed was also loaded with 5 wt % KOH. Based on the principle that the potassium ion catalyzes the cracking of tars into char or gas, it is proposed that this formed char is easily and fully gasifiable, leading to a feasible, continuous low-tar pyrolysis oil gasification process. The results show promise of deep tar removal under more severe conditions, resulting in a much smaller tar removal step afterward. This process would fit well into the concept where lignocellulose residues are first locally pyrolyzed to pyrolysis oil, after which they will be collected and gasified at a low temperature, of ∼700 °C, on a large scale.

This paper presents a process design for catalytic nonoxidative natural gas conversion to olefins and aromatics, highlighting the opportunities and challenges concerning industrial implementation. The optimal reactor conditions are 5 bar and 1000 °C. Heat exchange over the reactor is challenging due to the high temperature and low gas pressure. Recovery of ethylene is economically unattractive due to the low ethylene concentration in the product stream, leading to a methane-to-aromatics process, recycling ethylene. Benzene is the most valuable product at an efficiency of 0.31 kgbenzene/kgmethane with hydrogen as a major valuable byproduct. Naphthalene, with a low value, is unfortunately the dominant product, at 0.52 kgnaphthalene/kgmethane. It is suggested to hydrocrack the naphthalene to more valuable BTX products in an additional downstream process. The process is calculated to result in a 107 $ profit per ton CH4.