Steam hydrocarbon reforming

Here we shall briefly summarize the effects of individual poisons on various catalytic reactions taking place on automotive catalysts. There are three main catalytic processes oxidation of carbon monoxide and hydrocarbons and reduction of nitric oxide. Among secondary reactions there are undesirable ones which may produce small amounts of unregulated emissions, such as NH3, S03 (6), HCN (76, 77), or H2S under certain operating conditions. Among other secondary processes which are important for overall performance, in particular of three-way catalysts, there are water-gas shift, hydrocarbon-steam reforming, and oxygen transfer reactions. Specific information on the effect of poisons on these secondary processes is scarce. 

For hydrocarbon steam reforming, 95% conversion was achieved at GHSV values between 36 000 and 144 000 h 1 at very low reforming temperatures between 450 and 600 °C. Synthetic, sulfur free diesel was processed at a GHSV of 144 000 fT1 and an S/C ratio of 3 at a 530 °C reaction temperature. More than 90% conversion was achieved for almost 10 h duration. On the other hand, methanol reforming was performed at very high reaction temperature between 350 and 425 °C. 

To meeet the demands of high-temperature applications such as hydrocarbon steam reforming and partial oxidation reactions, nickel-based alloys are frequently taken into consideration [10]. 

Hydrocarbon Steam Reforming Tests in Microcatalytic Reactor. 

Coking resistant Nickel Catalysts for Hydrocarbon Steam Reforming Song Ruojun, Zhang Liangqu and Guo Shendu... 

COKING-RESISTANT NICKEL CATALYSTS FOR HYDROCARBON STEAM REFORMING... 

One of the main problems associated with hydrocarbon steam reforming over Ni is the deactivation of the Ni catalyst as a result of the formation of carbon deposits on Ni. The C-induced deactivation of Ni has been studied extensively [10,18,28-35], For example, Rostrup-Nielsen reported that steam reforming of various hquid fuels on Ni leads to the formation of encapsulating, whisker-like, or pyrolytic carbon on the catalyst [18, 30], To illustrate the problem of carbon poisoning, in Fig. 13.1 we show a transmission electron micrograph (TEM) of a Ni particle taken after steam reforming of propane at steam to carbon ratio of 1.5. The micrograph shows that carbon deposits are formed on Ni [16],... 

Table 2.6. Selected Kinetic Equations for Hydrocarbon Steam Reforming... 

Zhuang, Q., Qin, Y., and Chang, L. Promoting effect of cerium oxide in supported nickel catalyst for hydrocarbon steam-reforming. Applied Catalysis, 1991, 70 (1), 1. 

Chin, Y.-H., King, D.L., Roh, H.-S., Wang, Y., and Heald, S.M. Structure and reactivity investigations on supported bimetallic AuNi catalysts used for hydrocarbon steam reforming. Journal of Catalysis, 2006, 244 (2), 153. 

This chapter is concerned with the work reported in the literature on the steam reforming df hydrocarbons which has been done since 1974 when the earlier review by Ross was written. For continuity some reference has had to be made to research covered in that review and some work before 1974 not described there is included here. Hydrocarbon steam reforming is still a process of major importance for the manufacture of hydrogen, synthesis gases, and town gas and, in the last five years, for the production of substitute natural gas. The study of reactions between hydrocarbon and steam on catalytic surfaces has continued to be an area of interest, throwing light on the mechanism of hydrocarbon decomposition and on the properties, of metal surfaces. 

Although copper-based catalysts have long been known to have good WGS activities, sensitivity of those catalysts to poisons that were present in the coal-derived gas precluded them from being employed industrially. It is only due to a massive change from coal gasification to hydrocarbon steam reforming which produces much purer synthesis gas, that copper-based catalysts entered the scene of WGS processes. Since... 

Carbon can exist on the metal surfaces of nickel catalysts in a variety of forms. Hydrocarbon exposure to nickel crystallites at elevated temperature (> 700 K) can rapidly produce a mass of long-growing carbon filaments (1, 2) as identified in numerous experiments analyzed by transmission electron microscopy (TEM). Yet very reactive forms of surface carbon can exist, since carbon atoms chemisorbed on nickel surfaces apparently play a central role in the mechanism of several nickel-catalyzed reactions, such as hydrocarbon synthesis, (3, U, 5) hydrocarbon steam reforming, (6, 7) and hydrogenolysis (8). 

The purpose of our paper is to compare the behaviors of platinum,rhenium, iridium and rhodium under the same coking conditions (Cyclopentane, 400 0. Re and lr were chosen as they are usually added to Pt in reforming bimetallic catalysts. Rh was studied since it is the most active metal in hydrocarbon steam reforming (Refs. 5-7). 

HYDROCARBON STEAM REFORMING CATALYSTS - ALKALI INDUCED RESISTANCE TO CARBON FORMATION... 

Deactivation of supported nickel on alumina by coke and/or carbon formation is a serious problem in hydrocarbon steam reforming. Several ways have been used to prevent coke and/or carbon deposition. Among them certain additives (e.g. MgG, K2O) which promote... 

Catalyst deactivation is a common pathological phenomenon in many industrial reactions. In the case of hydrocarbon steam reforming to produce synthesis gas, catalyst activity loss may be due to coke arising from carbon deposition. Carbon lay-down usually occurs via undesired side reaction, namely ... 

The increasing demand for hydrogen in China is basically met by hydrocarbon steam reforming process. Presently there are 23 hydrogen production units in operation with a total capacity of 582,600 Nm /h [27]. 

The tolerance of Ni catalysts to carbon-induced deactivation in hydrocarbon steam reforming and partial oxidation reactions can be significantly improved by impregnating Ni with small amounts of Sn (0.2-1 wt% with respect to Ni for Ni particles with the diameter between 30 and 200 nm). " Based on DFT calculations, it was... 

Di Felice, L., Courson, C., land, N. et al. (2009) Catalytic biomass gasification simultaneous hydrocarbons steam reforming and COj capture in a fluidised bed reactor. Chemical Engineering Journal, 154, 375-383. 

Development of Catalyst Coatings for Hydrocarbon Steam Reforming in Microchannels... 

Hydrocarbon Steam Reforming in Microstructured Plate Heat Exchangers... 

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