Search Results

You are looking at 1 - 7 of 7 items for :

  • "microprocessing" x
  • All content x
Clear All
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

Abstract  

Routine production of81Rb, utilizing the82Kr(p, 2n)81Rb reaction with natural krypton gas is described. Development and construction of a fully automated gas target system controlled by microprocess or is presented. A new type of81Rb–81mKr generator based on the sorption of81Rb on ion-exchange paper was developed and investigated in operation. It may be used either for gas-phase or for liquid elution of81mKr for different medical applications.

Restricted access

Abstract  

Differential thermal analysis (DTA) was the first thermal analysis technique used to qualitatively characterize natural clays and respective curves has been used since more than 60 years as their ‘fingerprint’. With the development of microprocessed equipments in the last decades, derivative thermogravimetric (DTG) curves also may be used for this purpose in some cases, which also may allow a quantitative characterization of clay components. TG and DTG curves are more indicated than DTA or DSC curves to identify and to better analyze the several decomposition steps of natural or synthetic organoclays. These questions are discussed in applications developed to characterize Brazilian kaolinitic clays, bentonites and organophilic clays.

Restricted access

Abstract  

Aiming the use of the sewage sludge produced in one of the largest Brazilian wastewater treatment stations as a raw material for the ceramic industry, the sintering process of the ashes produced from its calcination was evaluated by heating microscopy thermal analysis (HMTA). From the microprocessed images, a method was developed to obtain HMTA dimensional change curves as a function of temperature, equivalent to those usually obtained from dilatometers or by thermomechanical analysis (TMA). The final product after sintering at 1050°C, characterized by X-ray fluorescence spectrometry, scanning electron microscopy and X-ray dispersive energy, indicates the presence of a vitreous phase containing phosphorus, which explains the good sintering properties of the studied calcined sludge, as shown from its HMTA dimensional change curve.

Restricted access

Abstract  

A thermogravimetric method is proposed for study of the kinetic parameters of coked HZSM-5 zeolite regeneration. The technique, which makes use of integral thermogravimetric curves, was optimized by microprocessed integrated mathematical methods. The kinetic parameters obtained from the TG curves are the activation energy, the rate constants, the half-life times, and in particular the coke removal time as a function of temperature. The activation energy calculated by using the Flynn and Wall kinetic method was 81.4 kJ mol−1. It was observed that, to remove 99% of the coke from the zeolite in a period of 1 h, it would be necessary to carry out thermo-oxidation at 748 K, with a dry air purge flow of 120 cm3 min−1.

Restricted access

in microprocess technology and its possible use for gas-liquid reactions and the oxidation of glucose ” Dencic , I. , Hessel , V. , de Croon , M. H. J. M. , Meuldijk , J. , van der Doelen , C. W. J. , Koch , K. ChemSusChem 2012 , 5 , 232

Open access

microprocessing and microwave heating ” F. Benaskar , A. Ben-Abdelmoumen , N. G. Patil , E.V. Rebrov , J. Meuldijk , L. A. Hulshof , V. Hessel , U. Krtschil , J. C. Schouten Journal of Flow Chemistry 2011 , 1 , 74 – 89

Restricted access