Catalytic Dehydration of Glycerine to Acrolein

The biodiesel production yields glycerine as a by-product in quantities around 10 vol% of produced biodiesel. Acrolein can be obtained from glycerine by a dehydration reaction. Catalytic processes in gas phase have been developed to obtain acrolein from a renewable feedstock using heterogeneous catalysts. The main process variables are the reaction temperature, the concentration of glycerol in water, and the space velocity in fixed-bed reactors. A thermodynamic study of the equilibrium has been made to estimate the conversion to equilibrium as a function of temperature. The reactors have been heated usually between 523 and 603 K. Generally, an aqueous glycerol solution is preheated in a preheating zone at a temperature enough to vaporize the feedstock, between 473 and 533 K, depending on the concentration of reactant required in the feed. Some of the most active catalysts in the gas-phase reaction (yield >70%) were NH4-La-β zeolite, Pd/LaY zeolite, hierarchical ZSM-5, WO3/ZrO2, WO3/TiO2, ZrOx-NbOx, WOx-NbOx, WO3-SiO2/ZrO2, NbOx-WOx/Al2O3, H3PO4-MCM-41, SAPO-40, NbPSi, Pd-H3PW12O40/Zr-MCM-41, H3PW12O40/Cs-SBA-15, H3PW12O40/Nb2O5, Cs-doped H4SiW12O40/Al2O3, H4SiW12O40/TiO2, and H4SiW12O40/SiO2

Heterogeneous chemical reactions—A cornerstone in emission reduction of local pollutants and greenhouse gases

The current state and challenges of advanced experimental and modeling methods for a better understanding of heterogeneous chemical reactions are discussed using examples from developing and future technologies in the area of emission reduction of local pollutants and greenhouse gases. In situ and operando experimental techniques using laser and X-ray absorption spectroscopy, for instance, are able to resolve spatial and temporal concentration and temperature profiles in the near-wall gas phase, the interphase and inside the solid bulk. They have been exploited for a better understanding of the interaction of chemical reactions and transport processes. The experimental elucidation of chemical conversion on the microscopic scale leads to elementary step-like surface reaction mechanisms. The microkinetic description of gas-surface reactions is still challenging due to the complex influence of the modification of the solid material itself on the microscopic scale during the chemical reaction, which is caused by intrinsic materials’ modifications due to adsorbed species and temperature variations. Furthermore, transient inlet and boundary conditions on the reactor scale have a strong impact on the material and reaction rate. In addition to thermochemical reactions, an additional complexity comes into play with electrochemical ones. This paper will discuss heterogeneous chemical reactions in the light of emerging technologies such as emission control of natural gas and hydrogen fueled engines, use of CO$_{2}$ in chemical (methanation, dry reforming) and steel industry (off-gas reforming), hydrogen production by pyrolysis of methane, small-scale ammonia synthesis and use, and recyclable carbon-free energy carriers. Hence, this article will also reveal a new playground and the potential of methods, know-how, and skills of the combustion community to significantly contribute to the solution of climate-change relevant challenges

State estimation techniques for on-line model adaptation: a case study in thermal cracking

This thesis deals with the implementation of a state estimation technique (EKF, Extended Kalman Filter) on a preexisting dynamic model of a steam cracker (PDAE, 227 differential variables, 14268 algebraic variables), using the dynamic process simulator gPROMS. Given few and reliable on-line measurements coming from the real plant, the estimator is able to predict the state of coking of the furnace by adapting the model prediction with the availble measurement

Polyoxometalates as alternative Mo precursors for methane dehydroaromatization on Mo/zsm-5 and Mo/mcm-22 catalysts

The conversion of methane into higher molecular weight hydrocarbons of greater added value has emerged as one of the grand challenges of the 21st century. The non-oxidative methane dehydroaromatization (hereafter MDA) reaction is a promising methane valorisation reaction since it transforms methane into added-value aromatics and olefins, namely benzene, naphthalene and ethylene. Molybdenum-promoted ZSM-5 zeolite has proven to be one of the most effective catalysts for MDA providing a shape-selective environment for the conversion of methane into benzene. However, one of the principle disadvantages of using aluminosilicates in the presence of methane is that the catalyst suffers from rapid deactivation induced by coke formation, which ultimately leads to a decrease in activity and aromatics selectivity, making the process unsuitable for large-scale industrial applications. Better control of the metal dispersion on the surface of the aluminosilicate supports represents a crucial factor to partially suppress catalyst coking and improve stability. Here we show how different molecular polyoxomolybdate (POM) anions can be used as alternative Mo precursors to conventional Mo salts for the preparation of catalysts for the MDA reaction. Molecular dynamics simulations and experimental testing were conducted to characterize the interphase interactions between polyoxomolybdates and zeolite surfaces at the atomistic level and to evaluate the MDA performance of different POM-based catalysts supported on ZSM-5 and MCM-22, respectively. The catalysts prepared using hexamolybdate anions, [Mo6O19]2-, were found to be more active and selective towards benzene than those employing the commercial heptamolybdate, [Mo7O24]6-. The Mo loading and dispersion of MoOx species were found to be the key factors leading to enhanced catalytic stability on ZSM-5 and MCM-22-based supports for MDA where the 5% Mo6/MCM-22 catalyst provided a constant aromatics yield above 7% for more than 18 hours time-on stream operating at 700 °C with a diluted methane flow under atmospheric pressure. The zeolitic catalysts prepared with the Mo6 precursor were found to be amongst the most promising MDA catalysts in the literature and the results of this study pave the way for the selection and use of different POMs as innovative metal precursors to formulate new catalysts and further improve the MDA reaction process

ESSE 2017. Proceedings of the International Conference on Environmental Science and Sustainable Energy

Environmental science is an interdisciplinary academic field that integrates physical-, biological-, and information sciences to study and solve environmental problems. ESSE - The International Conference on Environmental Science and Sustainable Energy provides a platform for experts, professionals, and researchers to share updated information and stimulate the communication with each other. In 2017 it was held in Suzhou, China June 23-25, 2017

Advances in Data-Driven Modeling and Global Optimization of Constrained Grey-Box Computational Systems

The effort to mimic a chemical plant’s operations or to design and operate a completely new technology in silico is a highly studied research field under process systems engineering. As the rising computation power allows us to simulate and model systems in greater detail through careful consideration of the underlying phenomena, the increasing use of complex simulation software and generation of multi-scale models that spans over multiple length and time scales calls for computationally efficient solution strategies that can handle problems with different complexities and characteristics. This work presents theoretical and algorithmic advancements for a range of challenging classes of mathematical programming problems through introducing new data-driven hybrid modeling and optimization strategies. First, theoretical and algorithmic advances for bi-level programming, multi-objective optimization, problems containing stiff differential algebraic equations, and nonlinear programming problems are presented. Each advancement is accompanied with an application from the grand challenges faced in the engineering domain including, food-energy-water nexus considerations, energy systems design with economic and environmental considerations, thermal cracking of natural gas liquids, and oil production optimization. Second, key modeling challenges in environmental and biomedical systems are addressed through employing advanced data analysis techniques. Chemical contaminants created during environmental emergencies, such as hurricanes, pose environmental and health related risks for exposure. The goal of this work is to alleviate challenges associated with understanding contaminant characteristics, their redistribution, and their biological potential through the use of data analytics

The predictive functional control and the management of constraints in GUANAY II autonomous underwater vehicle actuators

Autonomous underwater vehicle control has been a topic of research in the last decades. The challenges addressed vary depending on each research group's interests. In this paper, we focus on the predictive functional control (PFC), which is a control strategy that is easy to understand, install, tune, and optimize. PFC is being developed and applied in industrial applications, such as distillation, reactors, and furnaces. This paper presents the rst application of the PFC in autonomous underwater vehicles, as well as the simulation results of PFC, fuzzy, and gain scheduling controllers. Through simulations and navigation tests at sea, which successfully validate the performance of PFC strategy in motion control of autonomous underwater vehicles, PFC performance is compared with other control techniques such as fuzzy and gain scheduling control. The experimental tests presented here offer effective results concerning control objectives in high and intermediate levels of control. In high-level point, stabilization and path following scenarios are proven. In the intermediate levels, the results show that position and speed behaviors are improved using the PFC controller, which offers the smoothest behavior. The simulation depicting predictive functional control was the most effective regarding constraints management and control rate change in the Guanay II underwater vehicle actuator. The industry has not embraced the development of control theories for industrial systems because of the high investment in experts required to implement each technique successfully. However, this paper on the functional predictive control strategy evidences its easy implementation in several applications, making it a viable option for the industry given the short time needed to learn, implement, and operate, decreasing impact on the business and increasing immediacy.Peer ReviewedPostprint (author's final draft

Gas Capture Processes

This book introduces the recent technologies introduced for gases capture including CO2, CO, SO2, H2S, NOx, and H2. Various processes and theories for gas capture and removal are presented. The book provides a useful source of information for engineers and specialists, as well as for undergraduate and postgraduate students in the fields of environmental and chemical science and engineering

Quo Vadis Dry Reforming of Methane?—A Review on Its Chemical, Environmental, and Industrial Prospects

In recent years, the catalytic dry reforming of methane (DRM) has increasingly come into academic focus. The interesting aspect of this reaction is seemingly the conversion of CO2 and methane, two greenhouse gases, into a valuable synthesis gas (syngas) mixture with an otherwise unachievable but industrially relevant H2/CO ratio of one. In a possible scenario, the chemical conversion of CO2 and CH4 to syngas could be used in consecutive reactions to produce synthetic fuels, with combustion to harness the stored energy. Although the educts of DRM suggest a superior impact of this reaction to mitigate global warming, its potential as a chemical energy converter and greenhouse gas absorber has still to be elucidated. In this review article, we will provide insights into the industrial maturity of this reaction and critically discuss its applicability as a cornerstone in the energy transition. We derive these insights from assessing the current state of research and knowledge on DRM. We conclude that the entire industrial process of syngas production from two greenhouse gases, including heating with current technologies, releases at least 1.23 moles of CO2 per mol of CO2 converted in the catalytic reaction. Furthermore, we show that synthetic fuels derived from this reaction exhibit a negative carbon dioxide capturing efficiency which is similar to burning methane directly in the air. We also outline potential applications and introduce prospective technologies toward a net-zero CO2 strategy based on DRM