Main reforming processes

The many processes implemented today include the following  

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The main reforming processes for heavy hydrocarbons, as already mentioned for the case of methanol, are SR, partial oxidation, and ATR. Regarding the catalysts used, mainly four potential challenges have to be met [113] ... 

A catalytic reforming process produces similar products. The relative amounts may differ, however, depending on the catalyst selectivity and process conditions, the main product, of course, is a high octane C, -1- gasoline fraction. 

Natural gas and crude oils are the main sources for hydrocarbon intermediates or secondary raw materials for the production of petrochemicals. From natural gas, ethane and LPG are recovered for use as intermediates in the production of olefins and diolefms. Important chemicals such as methanol and ammonia are also based on methane via synthesis gas. On the other hand, refinery gases from different crude oil processing schemes are important sources for olefins and LPG. Crude oil distillates and residues are precursors for olefins and aromatics via cracking and reforming processes. This chapter reviews the properties of the different hydrocarbon intermediates—paraffins, olefins, diolefms, and aromatics. Petroleum fractions and residues as mixtures of different hydrocarbon classes and hydrocarbon derivatives are discussed separately at the end of the chapter. 

Natural gas consists mainly of methane together with some higher hydrocarbons (Tab. 8.1). Sulfur, if present, must be removed to a level of about 0.2 ppm prior to the steam reforming process as it poisons the catalyst. This is typically done by cata-lytically converting the sulfur present as thiols, thiophenes or COS into H2S, which is then adsorbed stochiometrically by ZnO, at 400 °C, upstream of the reactor. 

Any chemical derived from petroleum, the main refining processes being fractional distillation, catalytic cracking and platforming (reforming the constituents with the aid of a platinum catalyst). Since sulphur may be recovered from petroleum refining and since SBR, furnace black and processing oils are all petrochemicals it is... 

They used a Ni-containing catalyst. In contrast to steam reforming of methane, methane partial oxidation is exothermic. However, the partial oxidation requires pure oxygen, which is produced in expensive air separation units that are responsible for up to 40% of the cost of a synthesis gas plant (2) (in contrast, the steam reforming process does not require pure oxygen). Therefore, the catalytic partial oxidation of methane did not attract much interest for nearly half a century, and steam reforming of methane remained the main commercial process for synthesis gas manufacture. 

Typically, the prereforming process is performed in an adiabatic fixed-bed reactor upstream of the main reformer. In the pre-reformer, higher... 

At present, hydrogen is produced mainly by the steam-hydrocarbon reforming process (Section 14.3). This method can contribute to global warming because it produces C02 as a by-product. It may be possible, however, to capture the C02 and sequester it in depleted gas wells or deep saline aquifers, thus avoiding addition of C02 to the atmosphere. 

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. 

The necessary fuel processing of natural gas or other hydrocarbons and coal before its use in the SOFC changes the system design. The following investigations have been done for methane as the main component of natural gas to keep the calculations simple. A common type of fuel processing for hydrocarbons is the endothermic steam reforming process as shown for methane in Equation (2.105) with the heat demand Equation (2.106)... 

Ammonia manufacture from natural gas by the steam reforming process is well documented. Briefly, raw synthesis gas consisting mainly of H2, N2, and C02 is produced by primary and secondary steam reforming and CO shift conversion this is followed by bulk C02 removal, elimination of residual CO and CO2 through methanation, and ammonia synthesis. These basic steps... 

The Ni-based catalyst typically used in the prereforming process can act as a sulfur trap to remove traces of sulfur in the feed. This can improve the lifetime of the catalyst in the main reformer and also the WGS catalyst used in the downstream. 

Traditionally, the area of hydrogenation eatalysis has been attracting much attention because of its technological importance in petroleum refining and reforming processes [4]. Over the past two decades, hydrogenation catalysts have also become increasingly important in the industrial production of fine chemicals. The last area will be the main focus of this chapter. 

Thus, in the case of the entrained-bed (dual flow) reactor, the methane content is very low and does not require specific fractionation. In the fluidized bed reactor, hydrocarbons other than methane are not formed. With the moving bed technique, operating in countercurrent flow, the hydrocarbon content (CH , CvH ) is sometimes high enough to require their separation from the gas produced, and possibly their conversion by supplementary steam reforming. A more detailed analysis of the main gasification processes under development or already industrialized is given in Table 1.5. 

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