(165d) Combined Model-Based Experimental Analysis and Process Design Leading to a Profitable Butadiene Telomerization Process

Most chemical products can be obtained from a limited range of platform chemicals, which are mainly produced by large scale petrochemical processes. Amongst these platform chemicals, 1-octene is an important representative serving as intermediate in the production of a broad range of end products. The production by traditional synthesis routes, such as Fischer-Tropsch synthesis or the polymerization of ethylene, covers most of the worldwide demand of 1-octene. However, both synthesis routes require expensive purification. The reason is the unselective nature of the reaction resulting in a broad product spectrum of both processes.

In contrast, in 2007 a novel synthesis route to 1-octene has been implemented by Dow Chemicals on industrial scale in Tarragona. Its key step is the homogeneously catalyzed butadiene telomerization, which allows the utilization of the C4-stream from naphta crackers as cheap and easily available butadiene source [1]. Due to its high chemoselectivity this process has the potential to replace classical processes for the production of 1-octene. However, the bottleneck of the process is the high cost for catalyst regeneration, since the catalyst becomes inactive at the end of the reaction and has to be worked-up before recycling.

Jackstell et al. [2] proposed another catalyst for butadiene telomerization, which is based on palladium modified with 1,3-dimesityl-imidazol-2-ylidene (IMes). This monocarbene-palladium complex is even more selective than the commercial catalyst utilized by Dow and can be continuously separated and recycled, since it remains active throughout the reaction.

In this work, a novel process for this catalyst is designed by applying the model-based design framework for integrated reaction-separation processes recently published by our group [3]. This hierarchical framework structures the design task by three distinctive steps: In the first step, different flowsheet alternatives are generated. In the second step, these alternative flowsheets are evaluated with shortcut methods to identify the most promising process alternatives, which are finally modeled rigorously and optimized in the third step to calculate operating point and sizing information and finally to determine the cost-optimal process structure.

Based on the insights gained through a model-based kinetic study, a tailored flowsheet for the Pd/IMes catalyst is developed and evaluated with shortcut methods. Compared to the process with the Dow catalyst, the operating cost for the PD/IMes process are significantly lower. At the optimal operating point the cost for catalyst and base is decreased by 80% and, additionaly, the process requires 70% less energy for separation. Therefore, the PD/IMes process has the potential to replace classical processes for the production of 1-octene, such as Fischer Tropsch synthesis or the oligomerization of ethylene.

Acknowledgement

The research leading to these results has received funding from the European Community’s Seventh Framework Programme [FP7/2007-2013] for SYNFLOW under grant agreement n° 246461. Financial support for the second author by the Excellence Initiative of the German Federal and state governments through the Cluster of Excellence Tailor-Made Fuels from Biomass are also gratefully acknowledged.

References

[1] Bohley, R.C., Jacobsen, G.B., Pelt, H.L., Schaart, B.J., Schenk, M., van Oeffelen, D.A.G., 1992. Process for producing 1-octene. WO 92/10450.

[2] Jackstell, R., Gómez Andreu, M. Frisch, A. Selvakumar, K., Zapf, A. Klein, H., Spannenberg, A. Röttger, D., Briel, O., Karch, R., Beller, M., 2002. A highly efficient catalyst for the telomerization of 1,3-dienes with alcohols: First synthesis of a monocarbenepalladium(0)-olefin complex. Angewandte Chemie International Edition, 41(6), 986-989.

[3] Recker, S., Skiborowski, M., Redepenning, C., Marquardt, W., 2015. A unifying framework for optimization-based design of integrated reaction-separation processes. Computers & Chemical Engineering, doi:10.1016/j.compchemeng.2015.03.014.