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The synthesis of γ-valerolactone (GVL), a platform molecule that can be produced from lignocellulosic biomass, was performed in this work by hydrogenation of an alkyl levulinate over Ru/C. Kinetic models reported in the literature are typically not compared with rival alternatives, even if a discrimination study is needed to find the optimum operating conditions. Different surface reaction kinetic models were thus considered in this work, specifically addressing hydrogenation of butyl levulinate to GVL, where the latter was used as a solvent to minimize potential solvent interference with the reaction, including its evaporation. The Bayesian approach was applied to evaluate the probability of each model. It was found that non-competitive Langmuir-Hinshelwood with no dissociation of the hydrogen model has the highest posterior probability.

The production of platform molecules from the valorization of lignocellulosic biomass is increasing. Among these plateform molecules, γ-valerolactone (GVL) is a promising one and could be used for different industrial applications. This molecule is synthesized from levulinic acid (LA) or alkyl levulinates (AL) through a tandem hydrogenation/cyclization (lactonization) cascade. A lot of investigations have been carried out to develop the best catalyst for the hydrogenation step by using solely LA or AL. However, one should keep in mind that in the AL production via fructose alcoholysis, there is also LA production, and both are present in the product mixture during the further conversion. To the best of our knowledge, no article exists describing the hydrogenation of LA and AL simultaneously in one-pot. Also, the literature reporting the use of solid catalyst for the second cyclization step is rare. To fill this gap, the hydrogenation of levulinic acid and butyl levulinate was studied over Ru/C and Amberlite IR-120. Several kinetic models were evaluated via Bayesian inference and K-fold approach. The kinetic assessment showed that a non-competitive Langmuir-Hinshelwood with no dissociation of hydrogen where LA, BL and H2 are adsorbed on different sites (NCLH1.2) and non-competitive Langmuir-Hinshelwood with dissociation of hydrogen where LA, BL (butyl levulinate) and H2 are adsorbed on different sites (NCLH2.2) are the best model to describe this system. The presence of LA and Amberlite IR-120 allows to increase the kinetics of cyclization steps, and in fine to accelerate the production of GVL.

International audience; Biomass valorization to chemicals, biofuels or materials will be more and more important during this century. Production of γ-valerolactone (GVL) from the hydrogenation of levulinic acid is a good illustration of this tendency. GVL can also be produced from alkyl levulinates hydrogenation. Can we find a relationship between the structure and the kinetics of this reaction? Can we predict the kinetics of any alkyl levulinates by knowing the kinetics of another alkyl levulinate? This paper has studied these two questions by developing a kinetic model including the effect of gas-liquid mass transfer. We have demonstrated that the kinetics of hydrogenation of levulinic acid, methyl, ethyl and butyl levulinates to GVL using Ru/C follow the Taft equation, which is derived from Linear Free Energy Relationships. This equation measures the effects of polar and steric on a reaction series. We have demonstrated that polar effect of the reaction series is the most significant effect. This relationship can predict the values of kinetic constants just by knowing their structure.

International audience; The use of lignocellulosic biomass in the chemical industry can significantly contribute to respect the various international agreements on climate change. One of the most promising platform molecules issued from the lignocellulosic biomass hydrolysis is γ-valerolactone (GVL). GVL can be upgraded to valuable chemicals and produced by the hydrogenation of alkyl levulinates. Although these reactions are widely studied, seldom research focused on the solvent effect. To fill this gap, the effect of three different reaction mixtures with an excess of butyl levulinate (BL), of butanol and GVL was studied on the kinetics of BL hydrogenation to GVL over Ru/C. PC-SAFT (Perturbed-Chain Statistical Associating Fluid Theory) shows that the solubility of hydrogen is not constant during the reaction progress, and it was taken into account. To allow a fair comparison, kinetic models were developed using Bayesian statistics for each reaction mixture. The best performances were obtained when the reaction mixture has an excess of GVL.

With more than 350 GWh per year and thousands of installations around the world, biogas is an appealing strategy in the field of energy production and industrial waste optimization. In this sense, it is of paramount importance to address the risk associated with such plants, as an increasing trend of accidents have been recorded in the last 20 years. In this work, a representative biogas production plant was considered, and a risk assessment was carried out through the combination of Recursive Operability Analysis and Failure Mode and Effects Criticality Analysis. The methodology is rigorous and allows for both the identification and the quantification of accidental scenarios due to procedural errors and equipment failures, which miss in the literature for the case of biogas. The analysis allows the automatic generation of the Fault Trees for the identified Top Events, which can be numerically solved. Results show that the most critical accidental scenario in the biogas plant here considered is the formation of an explosive air-biogas mixture, which can occur in both anaerobic digester and condensate trap. The calculated probabilities agree with the results available in literature on similar plants. Pumps and Distributed Control System were found to be the most critical components.

One of the most common but promising processes for the production of paints and coatings is the free radical emulsion polymerization reaction involving different types of monomers. As it is also demonstrated by statistics concerning accidents in chemical industries, polymerizations are one of the most frequent causes of thermal runaway; therefore such syntheses require a very high level of control of all the operating variables, especially at full plant scale where safety problems are of paramount importance. The main aims of this work were the modeling and the industrial scale optimization of a complex polymerization process. Since four different monomers are involved in different proportions in such a process, the pseudo-homopolymer approach together with available literature correlations for the estimation of the main constitutive parameters of the system were used to solve the mathematical model and simulate the dynamics of the synthesis at the full plant scale. The proposed model and all the constitutive parameters estimates were validated through the comparison with both laboratory and full-scale experimental data, demonstrating a good agreement. Finally, the results of the optimization procedure were validated at laboratory scale.

Security threats are becoming an increasing concern for chemical sites and related infrastructures where relevant quantities of hazardous materials are processed, stored or transported. In the present study, security related events that affected chemical and process sites, and related infrastructures, were investigated. The aim of the study is to frame a clear picture of the threats affecting the chemical and process industry, and to issue lessons learnt from past events. A database of 300 security-related accidents was developed and populated, starting from European and American sources. Threat categories that caused such events were identified and analyzed. The attack modes were investigated. Important differences were found with respect to geographical areas and industrial sectors affected. The use of explosives (both military and improvised explosive devices) is by far the more frequent attack mode, although armed attacks and arson are also frequent events and may result in an in-depth penetration of the attackers. In recent years, cyber-attacks are also posing important threats. Lessons learnt call for the implementation of a specific security management system in the chemical and process industry, aiming at the physical and cyber protection of industrial sites.

Biogas is becoming an increasingly important resource of energy production from biomass, and a number of alternative technologies are proposed for its production and upgrading. However, in spite of the increasing number of accidents recorded, scarce attention was dedicated to date to the control and mitigation of biogas hazards. In this study, inherent safety of biogas technologies was addressed. A method for the selection of inherently safer alternatives during early design stages was further developed and combined to a Monte Carlo sensitivity analysis, accounting for uncertainty of input parameters and addressing the robustness of the ranking provided. The method was applied to the assessment of several alternative reference process schemes for biogas production and upgrading. The results allowed the identification of critical safety issues and the ranking of inherently safer solutions. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2713–2727, 2016

The interest in the epoxidation of vegetable oils is constantly growing in the chemical industry. The most common process is based on the oxidation of the unsaturated bonds by peroxyacids generated in situ, in the water phase, using concentrated hydrogen peroxide and the corresponding organic acid in presence of a mineral acid as catalyst. The overall epoxidation reaction is highly exothermic, hence operating conditions should be always addressed by safety considerations related to the possibility of runaway reactions. In this paper, best operating conditions and safety considerations have been defined for a complex reaction network for the epoxidation of soybean oil, which includes the decomposition reactions of the performic acid generated during the epoxidation. Furthermore, sensitivity-based reactor stability criteria have been applied and compared, for the design of an adequate Early Warning Detection System for the process.

The prediction of the consequences of a runaway reaction in terms of temperature and pressure evolution in a reactor requires the knowledge of the reaction kinetics, thermodynamics and fluid dynamics inside the vessel during venting. Such phenomena and their interaction are complex and yet to be fully understood, especially reactions where the pressure generation is totally or partially due to the production of permanent gases (gassy or hybrid systems). Moreover, these phenomena cannot be easily determined by laboratory scale experiments. In this paper, a dynamic model developed to simulate the behavior of an untempered reacting mixture during venting is presented. The model provides the temperature, pressure and mass inventory profiles before and during venting. A sensitivity study of the model was performed. This modeling work provides some insight regarding the interpretation of the data obtained from untempered system venting experiments. The outcome of this work contribute to improving the design of emergency relief systems for hybrid and gassy systems, where significant progress is still to be made in the experimental and modeling areas.

Low-thermal inertia experiments in the open cell configuration were carried out to perform a comprehensive sensitivity analysis of the parameters affecting the runaway self-decomposition of dicumyl peroxide (DCP). This study facilitates a better understanding on how concentration, initial back pressure, and fill level influence DCP runaway severity. The outcome of this experimental study was compared to previous adiabatic closed cell experiments, with the aim of clarifying the discrepancies reported in the literature and contributing to essential knowledge about self-decomposing peroxide systems. Results showed that the detected onset temperature, maximum temperature, maximum pressure, and time to maximum rate are affected by the configuration of the equipment and initial back pressure of the experiments, while the adiabatic temperature rise did not seem to be affected. The roles that the kinetics, fluid dynamics, and thermodynamics play on these observations is addressed and discussed through the manuscript.

Some recent accidents involving the bioenergy production and feedstock supply chain raised concern on the safety of such technologies. A survey of major accidents related to the production of bioenergy (intended as biomass, bioliquids/biofuels and biogas) was carried out, and a data repository was built, based on past accident reports available in the open literature and in specific databases. Data analysis shows that major accidents are increasing in recent years and their number is growing faster than bioenergy production. The results obtained represent an early warning concerning the major accident hazard of bioenergies, and suggest the importance of risk awareness and safety culture in bioenergy production, in the perspective of a safe and sustainable exploitation of renewable resources.