Comparison of jet loop and trickle-bed reactor performance in large-scale exploitation of glucose reductive aminolysis

Abstract

Commercial scale jet-loop and trickle bed reactor simulations have been performed for the reductive aminolysis of glucose with dimethylamine (DMA) in combination with an experimental assessment in a (large) lab-scale fed-batch and trickle bed reactor. Based on the intrinsic kinetics of the sequence of homogeneous and heterogeneously catalyzed reaction steps in the reductive aminolysis reaction network, coupled with a different flow pattern and catalyst-to-liquid ratio, significant differences in the yield of N,N,N’,N’-tetramethylethylenediamine (TMEDA) and N,N-dimethylaminoethanol (DMAE) can be expected for both reactor types. Yet, TMEDA is obtained in the highest yields irrespective of the reactor type. In the jet-loop reactor, which is operated overall as a batch reactor, an optimized TMEDA yield up to 57 % is simulated, while a non-negligible yield of DMAE, up to 12 %, is also achieved. The optimized operating conditions are such that they correspond to the high DMA to glucose ratio used during lab-scale fed-batch experimentations, also explaining why the jet-loop product spectrum is almost identical to the latter. This is ensured by the efficient heat-exchange in the jet-loop reactor, which is, in contrast, one of the main bottlenecks for exploitation of the reductive aminolysis in a trickle bed reactor. The second challenge to address in the trickle bed reactor is the limited extent of hydrogen transfer from gas to liquid, which can only be partially overcome by increasing the feed flow rates. While isothermal operation indicates TMEDA yields of about 60 %, non-isothermally simulated TMEDA yields only amount to 40 %. The latter yield loss was also validated experimentally in the trickle bed reactor and confirmed that avoiding degradation reactions remains challenging as it is critical in the reductive aminolysis of glucose.