VCM technology and Oxychlorination
Oxychlorination of ethylene is a key process step in the production of PVC (polyvinyl chloride) a thermoplastic produced by polymerisation of VCM (vinyl chloride monomer). INEOS ChlorVinyls, one of inGAP's industrial partners, is the leading producer of PVC in Europe, and has production facilities at Rafnes, Norway, which is almost entirely based on LPG from the Norwegian continental shelf, representing a significant value creation for Norwegian natural gas resources.
PVC is a thermoplastic (it can be melted and frozen into desired shapes repeatedly), its versatility ranging from building and aerospace products to pharmaceuticals. This makes PVC the second largest commodity plastic after polyethylene, and the PVC world production is expected to exceed 40 million tonnes per year by 2016.
Oxychlorination of ethylene is a catalytic process performed over a copper based heterogeneous catalyst in either a fluidized bed or a multitubular fixed bed reactor. The catalyst typically contains cupric chloride (CuCl2) as the primary active ingredient, impregnated on a porous support such as alumina, and may also contain numerous additives. Since the oxychlorination reaction is a highly exothermic reaction (releases energy as heat), the temperature rise and high volatility of active species are the main concerns. Deactivation of catalyst and production of unwanted chlorinated by-products causing high handling costs to the overall economy of the process. Despite of its commercial usage for more than 40 years, the deep understanding of the catalyst and its mechanism is still under investigation. inGAP has taken up this challenge and the aim of the activities within inGAP is to;
- Develop reaction kinetics based on fundamental understanding of the reaction mechanism.
- Gain understanding, at the atomic level, of the working catalytic system, particularly the role played by the additives and the carrier.
The work is carried out in collaboration between NTNU, University of Turin, University of Oslo and INEOS. The approach is to study the catalyst under working conditions by in-situ and in-operando techniques.
Our aim is to understand, at the atomic level, the role played by additives in the industrial catalyst. Our approach is to use a multi technique approach combined with expertise from industrial and academic partnerships. FTIR, UV-vis, XRD, EXAFS, XANES, CO-chemisoprtion ex-situ and in-situ, as well as traditional catalytic testing are our methods of choice. Several reports have already been published in international journals. Our studies so far show that a main challenge is to maintain the catalyst surface in an optimal state of chlorination, vital to achieve high activities and selectivities. Understanding the catalytic system under realistic conditions using combined characterisation techniques and systematic kinetic studies, gives an insight into the mechanism of the process and thereby provides ways of tuning the catalyst as desired. The results will be utilised in INEOS’ continuous efforts to improve the performance of the oxychlorination reactors and thereby the company’s competitiveness.