Minimising the industry's environmental impact
The EU-funded project SUPER sought to investigate innovative chemical processes as environmentally friendly alternatives to existing industrial processes. These new catalytic routes employ supercritical fluids (SCFs) as reaction media. SCFs have surpassed their critical temperature and critical pressure points where the substance in question can exist as a vapour and as a liquid in equilibrium. The use of SCFs like supercritical (SC) carbon dioxide (CO2) has been dubbed as environmentally safe and is posed as a viable alternative to currently used reaction media. The catalysis for the formation of cumene from disopropylbenzene is one that was explored as part of the SUPER project. Cumene is used as thinner for paints, enamels and is a component of high octane fuels. Cumene is further used for the manufacture of phenol and acetone among other substances. INSTM researchers tried to identify a new high-yielding process based on SC CO2 for the transalkylation of disopropylbenzene to cumene. Zeolites are considered suitable catalysts for this process, albeit at varying yields. Zeolites are a widely used group of inorganic porous minerals with a highly regular structure. The H-Y zeolite can result in cumene yields of up to 61% at temperatures of 200 degrees C and 130 atm, in the presence of SC CO2. As such in its native form the H-Y zeolite cannot produce the desired 80% and above yields. However, researchers have discovered that a dealumination procedure can result in a zeolite catalyst with 77% cumene yields. The correlation between catalyst composition and final product yield is an important one in this case since it paves way for further optimisation of this innovative process. One of the key next steps is the investigation of SC conditions on catalyst lifetime which is yet to be determined. This line of research is of particular interest to engineering firms seeking to improve their environmental record and explore alternatives to current processes.