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.
Dit onderzoek is uitgevoerd door LEI Wageningen UR en NMI (Nutriënten Management Instituut) in opdracht van het ministerie van Economische Zaken.
LEI Wageningen URWageningen, mei 2016 RAPPORT LEI 2016-034 ISBN 978-94-6257-778-7 Luesink, H.H., R. Postma, M.J. Smits, L. Van Schöll, en T.J. de Koeijer, 2016. Effect afzet mestverwerkingsproducten bij wettelijke status kunstmest of EG-meststof. Wageningen, LEI Wageningen UR (University & Research centre), LEI Rapport 2016-034. 64 blz.; 6 fig.; 6 tab.; 45 ref. Het ministerie van Economische Zaken (EZ) heeft LEI Wageningen UR en NMI (Nutriënten Management Instituut) gevraagd hoe de markt voor herwonnen nutriënten zich ontwikkelt wanneer er geharmoniseerde productspecificaties voor organische meststoffen gelden en wanneer kunstmestvervangers gemaakt uit dierlijke mest, wettelijk gelijk zijn gesteld aan kunstmest.De invloed van het wegvallen van die regelgeving is beperkt. De omvang van de verwerking van mest tot mineralenconcentraten zal wat toenemen, de kosten van export van mestproducten zullen iets lager worden en de poorttarieven van mestverwerkers kunnen met 1-2 euro per ton mest dalen (5-10%).The Dutch Ministry of Economic Affairs has asked LEI Wageningen UR and NMI (Nutriënten Management Instituut) how the market for reclaimed nutrients would develop if harmonised product specifications were to apply to organic fertilisers and if substitutes for artificial fertilisers made from animal manure were to be considered legally equivalent to artificial fertiliser.The influence of the scrapping of such regulations is limited. The scale of the processing of manure into mineral concentrates will increase a little, the costs of exporting manure products will be a little lower, and the gate fees for manure processers could decline by 1-2 euros per tonne of manure (5-10%). Deze vraag en de zes deelvragen (paragraaf 1.2) zijn beantwoord middels literatuuronderzoek (hoofdstuk 3 en 4), aanwezige expertise bij het LEI en NMI en het interviewen van stakeholders voor de volgende vier deelmarkten:• de binnenlandse markt (paragraaf 4.2)• de Europese markt (paragraaf 4.3)• de grondstoffenmarkt voor minerale meststoffen (paragraaf 4.4) en• overige markten (paragraaf 4.5).
Nitrite hydrogenation is studied in steady‐state as well as transient operation using a Pd catalyst in a tubular membrane contactor reactor. A negative reaction order in hydrogen in steady state operation proofs that hydrogen and nitrite adsorb competitively. In transient operation, feeding nitrite to the Pd surface fully covered with hydrogen results initially in very low conversion of nitrite, speeding up once hydrogen is removed from part of the Pd surface. Additional proof for competitive adsorption between hydrogen and nitrite is provided by the observation that exposure of a nitrite‐covered catalyst to hydrogen induces desorption of nitrite. Formation of ammonia in these experiments proceeds via two pathways, first via a fast reaction followed by extremely slow hydrogenation of adsorbed N atoms, which is kinetically not relevant. This information is relevant for designing effective and selective catalysts when operating at very low nitrite concentration.
The effect of addition of ethane and ethylene (C2) on methane coupling at 1000°C was investigated. A Fe/SiO2 catalyst was used to determine the contributions of catalytic as well as...
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