1494
Energy & Fuels 2004, 18, 1494-1499
Pilot Plant Study of Paraffin Upgrading by Hydrogenation over Ni-Mo/Al2O3 and Ni-W/Al2O3 Catalysts Jesu´s Sa´nchez,† Marı´a Fernanda Tallafigo,‡ Miguel A. Gilarranz,*,§ and Francisco Rodrı´guez# E.T.S.I. Minas, C/Rı´os Rosas, 21, 28003 Madrid, Spain, E.T.S.I. Caminos Canales y Puertos, Ciudad Universitaria, 28040 Madrid, Spain, Departamento de Ingenierı´a Quı´mica, Facultad de Quı´mica, Universidad Complutense de Madrid, 28040 Madrid, Spain, and AÄ rea de Ingenierı´a Quı´mica, Facultad de Ciencias, Universidad Auto´ noma de Madrid, 28049 Madrid, Spain Received March 2, 2004. Revised Manuscript Received June 18, 2004
The hydrogenation of microcrystalline raw paraffin from the dewaxing of heavy neutral oil over Ni-Mo/Al2O3 and Ni-W/Al2O3 catalysts was studied at the pilot plant scale. The diameter and pore structure of the catalyst showed a noticeable influence on the properties of treated paraffins. The use of catalysts with a particle size of 1.5-2.5 mm allowed us to reduce the severity of the reaction conditions. To obtain treated paraffins with acceptable Saybolt color values, temperatures of >310°C and pressures of >60 kg/cm2 were needed. High temperatures resulted in cracking reactions and high oil content, which can be prevented by high hydrogen pressure. The Ni-W catalyst showed higher activity and selectivity than Ni-Mo catalysts. Saybolt color values of >+30 and oil contents of +30 +12 0.65 5 pass
350 60 >+30 +13 0.87 5 not pass
350 40 >+26 +7 1.10
330 60 +27 +9 0.54 6 pass
not pass
For a space velocity of 0.5 h-1. Table 5. Hydrogenation of Raw Paraffin with Catalyst Ni6W14D25a parameter
temperature (°C) pressure (kg/cm2) Saybolt color UV stability, after 30 h oil content (wt %) sulfur content (ppm) carbonizable substances a
value 260 100 +23 +5 0.30 3 pass
For a space velocity of 0.5 h-1.
300 100 +30 +9 0.31 4 pass
330 100 >+30 +13 0.35 pass
350 100 >+30 +13 0.48 6 pass
350 40 +27 +17 0.79 not pass
350 60 >+30 +12 0.63 5 not pass
350 80 >+30 +12 0.60 4 pass
330 60 +30 +12 0.44 pass
330 80 >+30 +12 0.29 5 pass
330 140 >+30 +13 0.33 5 pass
310 60 +30 +12 0.26 pass
Paraffin Upgrading by Hydrogenation over Catalysts
the stability does not improve and the cracking reactions occur to a greater extent, as can be observed from the increase in oil content. Another characteristic of catalyst Ni6W14D25 is a higher selectivity, especially at low pressure and high temperature. The oil content of the treated paraffins remains at values of 310 °C and pressures of >60 kg/cm2 are needed to achieve acceptable Saybolt color values; however, high temperatures can lead to excessive cracking of paraffins and oil generation. The extent of the cracking reactions can be reduced, provided that the pressure is increased. The use of catalysts with a high load of active phase enables us to reduce the severity of the reaction conditions. Thus, Saybolt color values of >+30, stabilities of +12, and oil contents of
