Production of n-propyl acetate by reactive distillation : experimental and theoretical study

First steps of the development of a catalytic reactive distillation process for the production of n-propyl acetate based on experiments and simulations are proposed. The kinetics for homogeneously (sulphuric acid) and heterogeneously (Amberlyst 15) catalysed reaction were investigated and the constants for a pseudo-homogeneous model are presented. Pilot plant experiments were performed using a homogeneous strong acid catalyst in a packed column. A top-column decanter is used to withdraw the aqueous phase and to reflux the organic phase. Simulation results are in good agreement with experimental data. Thermodynamics nonidealities are taken into account using VLE and LLE NRTL interaction parameters. Alcohol conversion and n-propyl acetate purity may be dramatically increased just by adding to the pilot plant a stripping section in an additional column: six different configurations are identified to achieve such a production. The startup is studied in order to determine the best strategy to achieve steady-state conditions. The strong influence of the composition of the initial charging in the decanter can be seen and an initial charging of the two-phase top product leads to the fastest startup

Introducing Sustainability Assessment and Selection (SAS) into Chemical Engineering Education

Assessment of a sustainable process design centres on the three pillars of sustainability. However, satisfying all criteria is sometimes difficult. Nevertheless, it is important to have an effective and systematic tool for a concrete and justifiable decision. Introduction of such tool into chemical engineering education would be beneficial as students will encounter situations in making decision which may imply deciding on the best process design, suppliers, supply chain, etc. In light of this matter, we introduce a concept called sustainability assessment and selection (SAS) into Computer Aided Plant Design (CAPD) course at Technical University of Berlin. The idea of the methodology is to assess process designs and select one which is most sustainable. Within the framework of this course, a 1-day lecture has been conducted that touch on the methods to assess sustainable process design. It is also aimed to introduce systematic multi-criteria decision making methodology called analytic hierarchy process (AHP). A practical example in choosing n-butane isomerization process designs is illustrated. From the class evaluation we found that the response towards the idea was very promising. We believed the method would add an extra edge to the students especially in performing sustainability assessment and systematically solving multi optional problems that they may encounter in their career

Use of different pre-treated chromium leather shavings to produce biogas in continuous scale

Content: Leather goods are noble and sustainable but leather production may bear a potential for pollution. During leather manufacture high amounts of chromium shavings, wet by-products of the leather industry, are produced worldwide. Due to their chromium content they are disposed in landfill sites worldwide leading to long lasting environmental problems. They are stable towards temperatures of up to 110 °C and enzymatic degradation, preventing anaerobic digestion in a biogas plant. This stability is due to the three-dimensional native structure, typical for collagen, and additional chemical cross-links between the collagen fibers achieved by Cr3+ salts in the tanning step in tanneries. Therefore, hitherto chromium shavings are not utilized industrially to produce biogas. In order to ease enzymatic degradation, necessary to produce biogas, a previous denaturation of the native structure has to be carried out. Otherwise, the generation of biogas is hindered. In our projects, shavings were pre-treated thermally and mechanically by extrusion and hydrothermal methods. In previous works, we studied intensively the use of these shavings to produce biogas in batch scale and significant improvement was reached when using pre-treated shavings. In this work, a scale-up of the process was performed in a continuous reactor using pre-treated and untreated shavings to examine the feasibility of the considered method. Measuring different parameters along the anaerobic digestion, namely organic matter and volatile fatty acids content, it was possible to show that a higher loading rate can be used when feeding the reactor with pre-treated shavings instead of untreated shavings, which means a more economical process in an industrial scenario. Take-Away: The use of a pre-treatment improves the biogas production from chromium shaving