Medium pressure catalysis rig (DK4.5)

Medium pressure catalysis test-rig

The continuous test-rig was developed in-house to allow for steady-state catalytic evaluations of monolithic or grained samples under elevated pressures (up to 14 bar(a)) and temperatures of up to max. 160 ˚C. Administration of up to three permanent gases via MFC (MKS GM50A, range up to 1000 NmL/min) and one liquid via an HPLC pump (approx. range: 0.05 – 1 mL/min ; cooled pump head allowing for use of liquefied gases like 1-butene) with monitoring by a liquid CORI-FLOW meter. After evaporation of the liquid and merging with the gas stream, thorough mixing and dampening of pressure shocks (evaporating liquid) is achieved in a tube (Ø: 4cm) filled with glass beads. The homogenized mixture can be sent to: a) bypass; b) fixed bed reactor (Ø: 1 cm); c) monolith reactor (Ømonolith: 2.54 cm) equipped with retentate and permeate outlets. Thereafter, the gas mixture passes through a back-pressure valve (BPV) which maintains the reactors (and upstream equipment) at the required pressure. Finally, a manual needle valve allows part of the exit stream to be sent to a GC (Agilent 7890 gas chromatograph) instrument equipped with both a TCD and FID detector. An automatic emergency shutdown (ESD) system was implemented which gets triggered if one (or more) of the 9 heating zones get too hot or the pressure exceeds a defined level. ESD causes electricity supply to heating elements to be cut-off, stop further supply of gases by activating normally closed (NC) valves just downstream of MFCs/HPLC of flammable/explosive gases and release of existing pressure through normally open (NO) valves situated between the evaporator and reactors. The NC and NO safety valves are pneumatically driven in case of power outages.

The test-rig has been successfully used for long-term (up to 1300h) 24/7 unmanned evaluation of catalysts (grained and monolithic) using H2, CO and 1-butene feeds (hydroformylation reaction) at 10bar(a) and 120 ˚C without major incidences.

While evaluation of the monoliths at present is only possible either pushing the entire gas stream through the monolith’s outer walls (permeate walls) or inner channels (retentate mode), future upgrades including a second back-pressure valve and two additional flowmeters could allow for evaluation of monoliths with an outer membrane (adjustable trans membrane pressure / flow). This could e.g. broaden the instrument’s application range to include CO2 separation by membranes.

The uniqueness of the test-rig its ability to handle both grained and monolithic samples as well as the implementation of the ESD, which allows for unsupervised long-term testing of catalysts with potentially explosive gas mixtures. The presence of a permeate and retentate outlet makes upgrading (e.g. adding a second back pressure valve) to a membrane reactor (reaction & separation in one unit) possible.