Process Intensification Techniques Research Articles

Intensification Approaches for Biodiesel Synthesis from Waste Cooking Oil: A Review

The use of biodiesel as an alternative fuel has become more attractive recently because of its environmental benefits such as nontoxicity and biodegradability. However, due to the unfavorable economics and other problems for design and operation of large scale reactors, commercialization of biodiesel has not been significantly effective. The specific challenges in the synthesis route based on transesterification include higher separation times, high operating cost, high energy consumption, and low production efficiency due to equilibrium limitations. The present work highlights the potential use of waste cooking oil as a cheap and economical feedstock discussing the advantages of the process and limitations for transesterification reaction. Improvements in the synthesis process based on the different pretreatment methods and process intensifying techniques are discussed with specific reference to transesterification of waste cooking oil. Different physical and chemical pretreatment methods required for the preparation of feedstock include filtration, drying, acidic esterification, adsorption, crystallization, and distillation for the removal of fatty acids and other contaminants. The critical review also highlights the different process intensification techniques such as cavitational reactors, microwave irradiation, microchannel reactor, oscillatory flow reactor, use of cosolvent, and supercritical transesterification process that can be used for biodiesel production process with an objective of enhancing the reaction rate, reduction in the molar ratio of alcohol to oil, and energy input by intensifying the transport processes and overcoming the equilibrium limitations. Guidelines for the selection of optimum operating parameters have also been given with comparative analysis of the different approaches of process intensification. Finally, some recommendations have been made for the possible research that needs to be done for successful commercialization of biodiesel synthesis.

Semicontinuous Thermal Separation Systems

AbstractSince the year 2000, semicontinuous separation processes have been studied as a unique process intensification technique for the thermal separation of chemical mixtures. Typically, a single separation unit is used for multiple purposes with the aid of an auxiliary storage tank called a middle vessel. The system is operated cyclically but without startup or shutdown phases. As a result, multiple separation steps can be carried out with fewer capital expenses. In several cases, a significant profitability advantage over continuous or batch process alternatives has been shown, particularly for intermediate production capacities. The progress in semicontinuous systems is reviewed, including the development of semicontinuous ternary distillation, liquid‐liquid extraction, azeotrope distillation, reactive distillation, and semicontinuous systems with integrated reaction and distillation or extraction. Control and operational strategies for semicontinuous systems are reviewed, as well as heuristics for modeling and simulation.

Green chemistry and engineering: a practical design approach

Green chemistry and engineering: a practical design approach

Selective acetylene hydrogenation over core–shell magnetic Pd‐supported catalysts in a magnetically stabilized bed

AbstractA novel magnetic microspherical catalyst support with enough mechanical strength was prepared through coating Al2O3 on a magnetic core of NiFe2O4 spinel ferrite using the oil drop method to synthesize magnetic Pd‐supported catalyst for acetylene hydrogenation reaction. The synthesized core–shell composite Pd/Al2O3 catalyst shows high surface area and pore volume as well as sufficient saturated magnetization property, characterized by powder X‐ray diffraction, low‐temperature N2 adsorption–desorption analysis, and magnetic measurements. Catalytic performance of this magnetic Pd/Al2O3 catalyst was measured for acetylene hydrogenation reaction in a magnetically stabilized bed (MSB) reactor under different operation conditions. Under the optimal conditions of 353 K, 1.5 MPa and a gas hourly space velocity of 12,000 h−1, C2H2 conversion and C2H4 selectivity approximated 100% and 84%, respectively, over this magnetic Pd/Al2O3 catalyst in the MSB reactor, as a control over the commercial catalyst for hydrogenation reaction C2H2 conversion and C2H4 selectivity was near 37 and 64% under the similar conditions. Significant improvement of acetylene hydrogenation processes over this novel magnetic catalyst enlightens us a promising route to explore process intensification techniques through MSB. © 2008 American Institute of Chemical Engineers AIChE J, 2008

Reactive distillation: The front-runner of industrial process intensification: A full review of commercial applications, research, scale-up, design and operation

Most industrial scale reactive distillations (presently more than 150), operated worldwide today at capacities of 100–3000 ktonnes/y, and are reported in this paper. Most of these plants started up less than 15 years ago. The drivers, processes, systems, scale-up methods and partner collaborations for this rapid invasion of a new process intensified technique are explained in this paper. The business drivers are (a) economical (prosperity): variable cost, capital expenditure and energy requirement reduction. In all cases these are reduced by 20% or more, when compared to the classic set-up of a reactor followed by distillation. (b) Environmental (planet): lower emissions to the environment. In all cases carbon dioxide and diffusive emissions are reduced and (c) social (people): improvements on safely, health and society impact are obtained by lower reactive content, lower run away sensitivity and lower space occupation. These industrial reactive distillation systems comprise homogeneous and heterogeneous catalysed, irreversible and reversible reactions, covering large ranges of reactions, notably hydrogenations, hydrodesulfurisation, esterifications and etherification. Various commercial methods for packing heterogeneous catalyst in columns are now available. The systems comprise amongst others: multiple catalyst systems, gas and liquid internal recycle traffic over these catalyst systems, separation, mass flow, and enthalpy exchange. These are integrated optimally in a single vessel, a characteristic feature of process intensification. The scale-up methods applied from pilot plants to commercial scale are brute force and modelling. Technology providers CDTECH and Sulzer Chemtech have used these scale-up methods successfully. Barriers perceived and real have also been removed by these companies. Chemical manufacturing companies have also developed their own specific reactive distillations by their own research and development. These companies, both on their own and in consortia, also developed heuristic process synthesis rules and expert software to identify the attractiveness and technical feasibility of reactive distillation. Heuristic rules and expert software will be presented and supported by examples. Academic research also produced design methods to identify the feasibility of reactive distillation, to determine the feed locations, to select packing types, to sequence columns optimally and also produced methods to design, optimise and control the columns with steady state and dynamic simulation models. The rapid commercial scale implementation of reactive distillation by co-operation of partners in research, scale-up, design and reliable operation can also be seen as a model for rapid implementation of other process intensification techniques in the chemical industry.

Alternative multiphase reactors for fine chemicals: A world beyond stirred tanks?

Traditionally the intermediate scale and fine chemicals industries have relied on stirred tank reactors, operated continuously or more commonly batchwise, as the work horse of their manufacturing plant to the almost total exclusion of any other type of liquid reactor. The switch to continuous processing has generally been resisted on the basis that this compromises plant flexibility and thus, reduces capital productivity. While the stirred tank and the associated slurry catalyst are of course reliable and flexible to the demands of multi-product plant, it is not always easy to scale up the chemistry from the laboratory and variability in product arises from imperfections in the mixing. This problem is exacerbated for multiphase reactions where the non-uniformity in mixing and mass transfer can lead to significant variance in reaction rate and selectivity, resulting in loss of product quality and productivity. The problem is that while the stirred tank is convenient, it is not in fact a particularly effective mixing device. While historically the stirred tank was one of few options, times are changing. There are many reactor designs now available for multiphase contacting and reaction. Some of these are a proprietary improvement on the simple stirred pot while others are significantly different, such as trickle beds, bubble columns and the use eductors and loop reactors for intense gas/liquid mixing. Interest is increasing into applying process and reactor intensification techniques to batch production through use of small flow channels and structured catalysts, of which monoliths are the best known example. This is however, but one example of work on structured catalysts and reactors that is expected to have an impact on the intermediate scale and fine chemicals manufacturing in the near future.

5504257 Process for producing diisopropyl ether with removal of acid material

Most industrial scale reactive distillations (presently more than 150), operated worldwide today at capacities of 100–3000 ktonnes/y, and are reported in this paper. Most of these plants started up less than 15 years ago. The drivers, processes, systems, scale-up methods and partner collaborations for this rapid invasion of a new process intensified technique are explained in this paper.The business drivers are (a) economical (prosperity): variable cost, capital expenditure and energy requirement reduction. In all cases these are reduced by 20% or more, when compared to the classic set-up of a reactor followed by distillation. (b) Environmental (planet): lower emissions to the environment. In all cases carbon dioxide and diffusive emissions are reduced and (c) social (people): improvements on safely, health and society impact are obtained by lower reactive content, lower run away sensitivity and lower space occupation.These industrial reactive distillation systems comprise homogeneous and heterogeneous catalysed, irreversible and reversible reactions, covering large ranges of reactions, notably hydrogenations, hydrodesulfurisation, esterifications and etherification. Various commercial methods for packing heterogeneous catalyst in columns are now available.The systems comprise amongst others: multiple catalyst systems, gas and liquid internal recycle traffic over these catalyst systems, separation, mass flow, and enthalpy exchange. These are integrated optimally in a single vessel, a characteristic feature of process intensification.The scale-up methods applied from pilot plants to commercial scale are brute force and modelling.Technology providers CDTECH and Sulzer Chemtech have used these scale-up methods successfully. Barriers perceived and real have also been removed by these companies. Chemical manufacturing companies have also developed their own specific reactive distillations by their own research and development. These companies, both on their own and in consortia, also developed heuristic process synthesis rules and expert software to identify the attractiveness and technical feasibility of reactive distillation. Heuristic rules and expert software will be presented and supported by examples.Academic research also produced design methods to identify the feasibility of reactive distillation, to determine the feed locations, to select packing types, to sequence columns optimally and also produced methods to design, optimise and control the columns with steady state and dynamic simulation models.The rapid commercial scale implementation of reactive distillation by co-operation of partners in research, scale-up, design and reliable operation can also be seen as a model for rapid implementation of other process intensification techniques in the chemical industry.