Search Results

You are looking at 1 - 5 of 5 items for :

  • "catalyzed systems" x
  • All content x
Clear All

raised by 1.255 times in case of ADC-catalysed system to 2.655 times in case of PbC-catalysed system. However, burning rate of CuC-catalysed AN–HTPB propellant was only 0.160 mm s −1 which was lower than the burning rate of virgin one. This variation can

Restricted access

conversion. The maximum conversion rate is observed at conversions approximately around 20–30 and 10–20% for uncatalyzed and catalyzed system, respectively, indicating that such systems obey the autocatalytic kinetics model either in the presence or in

Restricted access

systematic shift in the curing temperature maxima with increasing concentration of catalyst. Δ H has been found to be lower for catalysed systems. In this study, the catalyst concentration varied from 0 to 30%, and Δ H was found to fall by 25% which is

Restricted access
Journal of Flow Chemistry
Authors: F. Benaskar, A. Ben-Abdelmoumen, N. G. Patil, E. V. Rebrov, J. Meuldijk, L. A. Hulshof, V. Hessel, U. Krtschil, and J. C. Schouten

Abstract

An extended cost study consisting of 14 process scenarios was carried out to envisage the cost impact of microprocessing and microwaves separately or in combination for two liquid-phase model reactions in fine-chemicals synthesis: (1) Ullmann C–O cross-coupling reaction and (2) the aspirin synthesis. The former, a Cu-catalyzed substitution reaction, was based on an experimental investigation, whereas the latter, a noncatalyzed aromatic esterification reaction, was based on literature data. The cost of 4-phenoxypyridine production, as a pharmaceutical intermediate in the synthesis of vancomycin or vancocin, was compared with that of the synthesis of aspirin, a key example of large-scale fine-chemical production plants. The operating costs in the Ullmann synthesis were found to be related to material-based process (reactant excess, pretreatment, and catalyst synthesis), whereas those in the aspirin synthesis appeared to be related to downstream-based process (workup, waste treatment). The impact of an integrated microwave heating and microprocessing system on profitability was demonstrated with respect to operational cost and chemical productivity. Different modes of microwave heating and catalyst supply were studied and compared with conventional oil-bath-heated systems in batch and continuous processes. The overall costs including profitability breakthrough for a competitive market price of product were obtained from various combinations of heating and processing. In case of the Ullmann synthesis, the CAPEX (capital expenditure) was negligible compared to the OPEX (operational expenditure), whereas in the aspirin synthesis, the CAPEX was found around 40%, both at a production scales of 1–10 kg/day using proposed upscale methods. The source of the catalyst strongly determined the profitability of a continuously operated Ullmann process due to its effect on the chemical performance. Higher energy efficiencies could be attained using single-mode microwave irradiation; however, the energy contribution to the overall cost was found to be negligible. Different scenarios provided a cost-feasible and profitable process; nevertheless, an integrated microwave heating and microflow processing led to a cost-efficient system using a micropacked-bed reactor in comparison to wall-coated microreactor, showing a profit margin of 20%.

Restricted access

-order reaction with auto-catalyzed system, characterized by the formation of some intermediate species that markedly accelerates the cross-linking reaction [ 11 ]. Considering preliminary observations, the peak maxima is the most reliable and reproducible data we

Restricted access