The Shell Middle Distillate Synthesis Process

Abstract

A description is given of the Shell Middle Distillate Synthesis (SMDS) process. In this two-stage process, which has been developed specifically for the production of middle distillates, a liquid product is obtained which consists typically of naphtha, kerosine and gasoil in the ratios 15:25:60 to 25:50:25. Both the kerosine and the gasoil have excellent blending properties: the smoke point of the kerosine can be over 45 mm and the gasoil has a cetane number in excess of 70. Starting from natural gas, a thermal efficiency of 60% for a stand-alone plant can be achieved by using Shell technology for both syngas manufacture and middle distillates synthesis. Apart from the synthesis per se, special attention is paid to the production of the synthesis gas with its consequences for the overall process efficiency and the impact on the environment. Over the past few years substantial cost reductions have been achieved from developments in catalyst R&D and from optimizing the reactor size, process line-up and manufacture of synthesis gas. Furthermore a simple Syncrude mode has been developed in addition to the SMDS kerosine and gasoil modes.