Adiabatic prereforming

T.S. Christensen, Adiabatic Prereforming of Hydrocarbons - an Important Step in Syngas Production , Appl. Catal. A, 138 285-309 (1996). 

Catalyst Deactivation in Adiabatic Prereforming Experimental Methods and Models for Prediction of Performance... 

Figure 1. Temperature profiles in an industrial, adiabatic prereformer operating on naphtha feed in a H2-plant. H2O/C = 3.5 P = 26 bar Topsoe RKNGR Catalyst.

Figure 2. Typical installation of an adiabatic prereformer unit.

Rostrup-Nielsen found that the intrinsic reaction rate, rj, for methane steam reforming is correlated with the sulphur coverage by equation 6 (2). In the adiabatic prereformer, the sulphur acts as a pore mouth poison and as the reactions are restricted by pore diffusion 2,8), the effective activity of the sulphur poisoned catalyst pellet can be described by an empirical relation, equation 7, between the effective pellet reaction rate, rp, and the average sulphur coverage, 0av (7/... 

Table n Carbon Morphologies on Adiabatic Prereforming Catalysts found by H2-TPR. Heating Rate = 6 C/min... 

The individual catalyst sample typically shows the presence of 2-4 peaks and Figure 5 shows a TPR diagram for a catalyst that has been in operation for 6 months in an adiabatic prereformer with a naphtha feedstock at relative low temperature. Three peaks have been identified for this catalyst and they are ascribed to chemisorbed carbon (a-type) at 300°C, gum (P-type) at 480°C and the platelet/pyrolytic carbon (e-type) at 650°C. In addition some graphitized carbon is also observed as a weak peak at high temperature around 950°C. 

Figure 10. Performance test of adiabatic prereforming on naphtha feed. Temperature profiles from an pseudo-adiabatic prereformer. H2O/C = 1.5 P = 25 bar Topsoe RKNGR Catalyst.

The major advantages of incorporating an adiabatic prereforming step in reforming of high hydrocarbons include the following ... 

A wide variety of fuels such as diesel, jet fuel, and NATO F-76 have been reformed using adiabatic prereformers.103 Since the prereforming process is generally carried out at low temperatures, the catalyst must be highly active. Industries... 

Figure 2.16. Temperature profile for the adiabatic prereforming of jet fuel and diesel over Topsoe RKNGR catalyst. Adapted from Rostrup-Nielsen et al.10...

As has been discussed in Section 2.3.6, the use of an adiabatic prereformer also helps in alleviating the risk of carbon formation in the steam reforming of higher... 

Christensen, T.S. Adiabatic prereforming of hydrocarbons—An important step in syngas production. Applied Catalysis. A, General, 1996, 138 (2), 285. 

The activity of the catalyst is roughly proportional to the surface area of nickel used. In an adiabatic prereformer, a high activity is desired to maximize the space velocity. In a tubular reformer the activity may be of less significance because the reactor volume is settled by mechanical criteria. Most industrial tubular reformers operate at space velocities of 2000-4000 hr However, equilibrium conversion can be... 

A typical process diagram for producing syngas with ATR is shown in Fig. 11. Adiabatic prereforming... 

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