Packings for fixed bed reactors and reactive distillation

Abstract

Trickle-bed reactors in which gas and liquid cocurrently flow downward through a packed catalyst bed are common in the chemical and petroleum industries. The recent development of more active catalysts is pushing commercial operations to higher flowrates, towards the pulsing flow regime and to smaller catalyst particles. A new development of BASF tries to improve trickle-bed reactors by installing corrugated distillation packings within the reactor and pouring catalyst particles into the packing. By using a packing in a reactor a mechanical support to the catalyst is provided, the pressure drop is reduced, and higher liquid-throughputs are possible. The packing also leads to an onset of pulsing at higher liquid and gas loads. Hydrodynamic studies of trickle-bed reactors with and without packings were conducted over a series of catalysts. The measurements include pressure drop, loading capacity and abrasion. The experiments were conducted at high gas and liquid flow rates and at low gas and liquid flow rates. The hydrodynamic regimes have been characterized. For the application of this system to catalytic distillation a new kind of packing, the so-called multi-channel packing, was developed to obtain higher gas throughputs. By simply alternating packings with high and low specific surface areas the gas throughput can be increased significantly. Hydrodynamic studies were conducted for packings with different catalyst contents. The measurements include pressure drop, flooding point, liquid hold-up, and residence time.