Search

This study addresses the critical need for effective risk assessment and mitigation strategies in academic research environments. As research laboratories engage in increasingly complex projects, ensuring the safety of personnel, equipment, and the surrounding environment becomes paramount. These settings are prone to various vulnerabilities, including manual operations, transient states, and diverse training backgrounds. This work presents a case study focusing on the potential hazards and risks associated with Fischer-Tropsch synthesis. The analysis examines critical factors such as catalyst use, high-temperature reactions, potential by-products, and the influence of human error during manual operations. Utilizing a systematic approach that incorporates interaction matrices and HAZOP analysis, the study identifies potential undesired scenarios, ranging from minor incidents to severe consequences, and evaluates their likelihood and impact. In response to the identified risks, the paper proposes targeted mitigation measures specifically designed for the Fischer-Tropsch experimental setting, structured as layers of protection. The findings of this research offer valuable insights into laboratory safety in academic settings, providing a risk assessment and mitigation model adaptable to various experimental setups. By integrating theoretical frameworks with practical applications, this study aims to enhance safety standards in academic laboratories conducting Fischer-Tropsch synthesis and establish a foundation for continuous improvement in laboratory practices.

The liquid-phase hydrogenation of muconic acid (MA) to produce bio-adipic acid (AdA) is a prominent environmentally friendly chemical process, that can be achieved through two distinct methodologies: catalytic direct hydrogenation using molecular hydrogen (H2), or catalytic transfer hydrogenation utilizing a hydrogen donor. In this study, both approaches were explored, with formic acid (FA) selected as the hydrogen source for the latter method. Palladium-based catalysts were chosen for these processes. Metal’s nanoparticles (NPs) were supported on high-temperature heat-treated carbon nanofibers (HHT-CNFs) due to their known ability to enhance the stability of this metal catalyst. To assess the impact of support functionalization on catalyst stability, the HHT-CNFs were further functionalized with phosphorus and oxygen to obtain HHT-P and HHT-O, respectively. In the hydrogenation reaction, catalysts supported on functionalized supports exhibited higher catalytic activity and stability compared to Pd/HHT, reaching an AdA yield of about 80% in less than 2 h in batch reactor. The hydrogen-transfer process also yielded promising results, particularly with the 1%Pd/HHT-P catalyst. This work highlights the efficacy of support functionalization in improving catalyst performance, particularly when formic acid is used as a safer and more cost-effective hydrogen donor in the hydrogen-transfer process.

CO2-FTS is among the most viable methods for converting CO2 into useful chemicals and fuels in order to minimize CO2 emissions. Due to its chemical inertness, however, effective conversion continues to be a difficulty. The challenges in terms of yield and mechanism have attracted the interest of different research groups in the development of a new carbon dioxide hydrogenation catalysts, capable of reaching satisfactory results. In this work, a selection of nano ternary hydrotalcites (HTlc) were synthesized with and without ultrasound in order to develop active Fe-based catalysts for the Fischer–Tropsch synthesis. HTlc consists mostly of metal hydroxides in which different metal atoms are uniformly distributed at the atomic level. The reaction was carried in a lab scale plant in a fixed bed configuration. All fresh and used catalysts were examined and characterized using XRPD, ICP-OES, SEM, TEM, BET. Ternary HTlc composed of Mg, Cu, and Fe was synthesized using an ultrasound-assisted co-precipitation technique (MCF-US). HTlc was tested for carbon dioxide hydrogenation reaction with a study concerning different H2/CO2 ratios in order to evaluate the product distribution as well as the efficiency of the catalyst itself. The CO2 conversion resulted higher and more stable in feeds with higher H2 quantities. The selectivity towards higher chain hydrocarbons was higher for lower H2/CO2 ratios whereas methane and carbon monoxide selectivities were adequately low.

Due to hydrogen storage and transport problem, a concrete and immediate solution is the exploitation of the gas pipelines now used for natural gas. In this regard, this work aims to evaluate two main aspects that must be taken into account to make this approach possible: the separation of hydrogen from natural gas-hydrogen mixture and the odorization of the latter, in order to provide the safety of the pipelines. Therefore, the first part of this study is the evaluation of the efficiency of a purification system in presence of a variable quantity of methane in the inner stream. For these purposes, electrochemical hydrogen compression (EHC) system was selected, due to the great advantage of allowing both purification and compression in a single device. Different methane-hydrogen mixtures were taken into consideration, going to evaluate how an increasing amount of methane affects the efficiency of the system. The second part of this work is focused on a further development of a previous simulation study related to a possible process for natural gas-hydrogen mixtures odorization systems using AVEVA's PRO II software. As odorant, GASODOR S-FREE was taken into consideration, thanks to the fact that this is a common odorant used for methane with the great advantage of not containing sulfur, unlike THT and mercaptans.

Plastic pollution is a significant environmental issue, and recycling has been identified as one of the ways to reduce its impact. This review provides therefore a brief overview of the various processes involved in recycling of polyamide plastic waste. Nylon is a material extensively utilized in the creation of clothes, textiles, and other products thanks to its high mechanical and thermal properties, as well as its strength and durability. This latter feature turns in a very slow decomposition if polyamide-based objects are abandoned in the environment, making it a significant environmental pollutant. The review covers all the possible recycling processes for this material, that are mechanical recycling, which involves shredding and melting plastic waste to make new products, solvent dissolution, where a solvent selectively dissolved only the desired polymer leaving behind the unwanted impurities, and chemical recycling, which uses chemical reactions to break down plastic waste into its chemical constituent parts, i.e. Monomers. The advantages and limitations of these processes are discussed.

One of the most important goals of this century is the exploitation of hydrogen as green energy carrier. Due to its storage and transportation problem, a concrete and immediate solution is the exploitation of the gas pipelines now used for natural gas. In this regard, safety is of paramount importance; indeed, like natural gas, hydrogen is an odourless and colourless flammable gas. To solve this problem a system of hydrogen odorization is to implement. This work is aimed at the investigation of a possible process for hydrogen odorization, focused on pure hydrogen and natural gas-hydrogen mixtures systems, to simulate a possible real gas pipeline. The odorization system considered in this work is called INGRID, developed by Regas Srl, a partner company for this project. Starting from INGRID’s specifications, a simulation model was then developed using AVEVA's PRO II software on the basis of the thermodynamic liquid-vapor equilibria of the mixture. As odorant, tetrahydrothiophene (THT) was taken into consideration, thanks to the fact that this is the most used odorant and so more experimental data are available in the literature. This system has proved to be effective in the odorization of both pure hydrogen and hydrogen-natural gas mixture.

Two different groups of MgCuFe catalysts derived from hydrotalcite-like precursors were prepared through ultrasound-assisted (US) co-precipitation and solvent-free ball milling methods (BM). The catalysts were activated at 623°K, 1.5 MPa for 4 h in syngas, and their performances in the production of fuels through Fischer–Tropsch (FT) synthesis were evaluated in a fixed bed reactor at temperatures ranging from 473° to 573°K and 2 MPa and H2/CO molar ratio of 2. The physicochemical properties of the fresh and spent catalysts were investigated and characterized using different methods, including XRPD, ICP-OES, SEM, and TEM. Catalysts displayed similar catalytic activity for both BM and US with minor differences when operating at temperatures from 473° to 523°K. The results hint at the possibility of using synthetic hydrotalcites as Fe-based catalysts for the Fischer–Tropsch synthesis.

The hydrogenation of muconic acid (MA) to bio-adipic acid (AdA) is one of the green chemical processes that has attracted the most interest in recent years. Indeed, MA can be readily obtained from biomass through fermentative processes. Here, we aimed to investigate the synergic effect of electronic promotion that the addition of a second metal, even in small quantities, can have on Pd-based catalyst, known for its low stability. Ni and Zn were taken into consideration and two different catalysts (1%Pd8Ni2/HHT and 1%Pd8Zn2/HHT) were synthetized by sol immobilization method and supported on high-temperature, heat-treated carbon nanofibers (HHT-CNFs) that are known to enhance the stability of palladium. The catalysts were tested in MA hydrogenation and thoroughly characterized by TEM, ICP, and XPS analysis to unveil the effect of the second metal. To solve the solubility issue and have a starting material as similar as feasible to the post-fermentation conditions of the biomass, sodium muconate salt was chosen as a substrate for the reaction. All of the synthetized bimetallic catalysts showed a higher activity than monometallic Pd and better stability during the recycling tests, pointing out that even a small amount of these two metals can increase the catalytic properties of monometallic Pd.

The aim of this work is to evaluate the potential application of a new sustainable technology, called Acid Gas to Syngas, on steam reforming process in order to reduce the carbon dioxide emissions. Indeed, steam reforming has high emissions of carbon dioxide, at almost 7 kg of carbon dioxide per 1 kg of hydrogen produced. The key idea of the new technology is to convert carbon dioxide and hydrogen sulfide coming from natural gas desulfurization into additional hydrogen. Coupling different software, i.e. Aspen HYSYS and MATLAB, a complete plant model, able to manage the recycle of unconverted acid gases, has been developed. The importance of introduced innovations is highlighted and a comparison between the old process and the new one with Acid Gas to Syngas technology is built up. With Acid Gas to Syngas technology the natural gas consumption and carbon dioxide emissions can be reduced up to 3%.

The use of virtual immersive laboratories is an appealing and synergistic possibility for education in science, technology and engineering, complementary to experimental activities performed in laboratory or exercises delivered in traditional rooms. A new educational project, called Eye4edu, proposed different exercises on a virtual immersive Crude Distillation Unit (VCDU), with the aim to apply an active scenario for the learning of the structure of the single unit operations, the whole plant and the control and intervention operating procedures. The project was proposed to the bachelor and master students for the degree in Industrial Chemistry in the Milan University in the years 2019 and 2020. VCDU is based on the combination of the action of “Aveva XR for Training”, formerly Eyesim, and Dynsim software, from Aveva Company, for the physical representation and the dynamic chemical behaviour of the plant. Several exercises on the plant were proposed to the students both for practical and management operations in the plant. The students were required to work on the basis of the information available in the technical documents, as PFD and P&ID. The project was proposed both in presence and as distance learning, respectively before and during the health emergency due to SARS-CoV-2 pandemic. The description of the virtual laboratory and an analysis of its use and educational impact in face-to-face and remote delivery is reported in this paper.

Nowadays environmental sustainability is a fundamental requirement for the development of any process. In this regard, European Union applied directives on emission reduction commitments. In such circumstances, it is mandatory for industries or facilities to adopt proper pollution control measures to meet the requirements.The absorption process can be a simple, safe, regenerative and recovery technique, selective for the species. The aim of this work is to study the purification process of polluted air containing volatile organic compounds by absorption towers. The evaluation of the feasibility of the process and the effects of operative conditions on the efficiency will be discussed.Ethyl acetate was selected as a representative volatile organic compound chemical model. We experimentally purified air containing this pollutant at different concentrations by absorption with pure water, changing the temperature and the ratio between water and air flowrate. We investigated the effect of different packagings and their height using two columns: the first one with Sulzer rings and the second one with Raschig structured packaging. Finally, the effect of recycled solvent in the absorption process was considered.PRO/II software simulator enabled a steady-state simulation of the tests obtaining an excellent fitting of the experimental data.

In recent times, the methanol was employed in numerous innovative applications and is a key compound widely used as a building block or intermediate for producing synthetic hydrocarbons, solvents, energy storage medium and fuel. It is a source of clean, sustainable energy that can be produced from traditional and renewable sources: natural gas, coal, biomass, landfill gas and power plant or industrial emissions. An innovative methanol production process from coal gasification is proposed in this work. A suitable comparison between the traditional coal to methanol process and the novel one is provided and deeply discussed. The most important features, with respect to the traditional ones, are the lower carbon dioxide emissions (about 0.3%) and the higher methanol production (about 0.5%) without any addition of primary sources. Moreover, it is demonstrated that a coal feed/fuel with a high sulfur content allows higher reductions of carbon dioxide emissions. The key idea is to convert hydrogen sulfide and carbon dioxide into syngas (a mixture of hydrogen and carbon monoxide) by means of a regenerative thermal reactor. This is the Acid Gas to Syngas technology, a completely new and effective route of processing acid gases. The main concept is to feed an optimal ratio of hydrogen sulphide and carbon monoxide and to preheat the inlet acid gas before the combustion. The reactor is simulated using a detailed kinetic scheme.

The hydrogenation reaction of muconic acid, produced from biomass using fermentative processes, to bio-adipic acid is one of the most appealing green emerging chemical process. This reaction can be promoted by catalysts based on a metal belonging to the platinum group, and the use of a second metal can preserve and increase their activity. Pd–Au bimetallic nanoparticle samples supported on high-temperature, heat-treated carbon nanofibers were prepared using the sol immobilization method, changing the Pd–Au molar ratio. These catalysts were characterized by TEM, STEM, and XPS analysis and tested in a batch reactor pressurized with hydrogen, where muconic acid dissolved in water was converted to adipic acid. The synthesized Pd–Au bimetallic catalysts showed higher activity than monometallic Au and Pd material and better stability during the recycling tests. Moreover, the selectivity toward the mono-unsaturated changed by decreasing the Pd/Au molar ratio: the higher the amount of gold, the higher the selectivity toward the intermediates.

The sustainable development has recently become the cornerstone of the environmental policy worldwide and a leading principle for resource management. The philosophy lies in a continuous demand of innovative choices able to ensure the existing productive systems survival through a new design paradigm shift. In this regard, the technological innovation should be always driven by the sustainability concept: the economic, societal and environmental impact ought to be continuously fostered to the systems' sustainable improvement. This demanding goal can be accomplished with a blended Life Cycle (LCA) and Life Risk (LRA) Assessment to highlight the process potential health and environmental impacts. LRA is the process in which imposed risks by the inherent hazards linked to a process are continuously assessed (quantitatively or qualitatively). LCA instead is the process that analyses and assesses the environmental impact of a material, product or service throughout its entire life cycle. LCA and LRA are typically driven by two different approaches, respectively a deterministic and a stochastic approach. This usually drives an unconnected use of LCA and LRA in the quantification of products and processes potential impact and determines controversial decisions with respect to a balance between environmental impacts and operational risks. The new paradigm suggests a unified blended LCA - LRA approach that is applied at a preliminary stage to an innovative Acid Gas to Syngas (AG2S) process for CO2 emission reduction and on-site reuse, avoiding the costly and hazardous transportation step.

Separation processes represent one of the most important operation in chemical industry. The most used techniques are distillation and absorption. The Industrial Chemistry Bachelor’s Degree program at the University of Milano, Chemistry Department, includes a third-year course titled “Industrial Plants with Laboratory”. This laboratory (six university credits course) is devoted to separation processes with an average annual attendance of about 80 people. An experience concerning the use of an absorption column is proposed to the students. A 1 m height column with an internal diameter of 0.044 m, filled with Sulzer-type structural bodies is used for data collection in steady state conditions. Water purifies a mixture of a VOC (acetone) and air in counter current. With the collected data, students check the material balance on the column and, knowing the height of the column, determine the global diffusion coefficients. Moreover, the software PRO II 9.3 by AVEVA is used for the simulation of the plant. The comparison between experimental and simulated data is a key aspect of the laboratory and guarantees a cross-check of both activities. Students evaluation of the course is strongly positive.

A new process for oxygen enriched air (EA) production has been applied to Claus Process. This process is simple and requires few process units. Matlab and Aspen Hysys have been used for simulations and system sizing. The results demonstrate that it could be an alternative to traditional EA processes from an economical point of view.

Recently, we have witnessed a booming development of composites and multi-dopant metal oxides to be employed as novel photocatalysts. Yet the practical application of photocatalysis for environmental purposes is still elusive. Concerns about the unknown fate and toxicity of nanoparticles, unsatisfactory performance in real conditions, mass transfer limitations and durability issues have so far discouraged investments in full-scale applications of photocatalysis. Herein, we provide a critical overview of the main challenges that are limiting large-scale application of photocatalysis in air and water/wastewater purification. We then discuss the main approaches reported in the literature to tackle these shortcomings, such as the design of photocatalytic reactors that retain the photocatalyst, the study of degradation of micropollutants in different water matrices, and the development of gas-phase reactors with optimized contact time and irradiation. Furthermore, we provide a critical analysis of research–practice gaps such as treatment of real water and air samples, degradation of pollutants with actual environmental concentrations, photocatalyst deactivation, and cost and environmental life-cycle assessment.

The effect of support, stabilizing agent, and Pd nanoparticles (NPs) size was studied for sodium muconate and t,t-muconic acid hydrogenation to bio-adipic acid. Three different activated carbons (AC) were used (Norit, KB, and G60) and carbon morphology did not affect the substrate conversion, but it greatly influenced the adipic acid yield. 1% Pd/KB Darco catalyst, which has the highest surface area and Pd surface exposure, and the smallest NPs size displayed the highest activity. Furthermore, the effect of the amount of the protective agent was studied varying metal/protective agent weight ratios in the range of 1/0.00−1/1.20, using KB as the chosen support. For sodium muconate reduction 1% Pd/KB_1.2 catalyst gave the best results in terms of activity (0.73 s−1), conversion, and adipic acid yield (94.8%), while for t,t-muconic acid hydrogenation the best activity result (0.85 s−1) was obtained with 1% Pd/KB_0.0 catalyst. Correlating the results obtained from XPS and TEM analyses with catalytic results, we found that the amount of PVA (polyvinyl alcohol) influences mean Pd NPs size, Pd(0)/Pd(II) ratio, and Pd surface exposure. Pd(0)/Pd(II) ratio and Pd NPs size affected adipic acid yield and activity during sodium muconate hydrogenation, respectively, while adipic acid yield was related by exposed Pd amount during t,t-muconic acid hydrogenation. The synthesized catalysts showed higher activity than commercial 5% Pd/AC.

In the fine chemical industry, a number of exothermic reaction processes are better performed under reflux conditions. Such an operating regime of the reactor allows for removing the reaction heat at a self-controlling temperature, hence preventing peaks of the conversion rate with their related thermal effects. Moreover, when the desired reaction generates a low volatility product, which can further react with a non-selective reactant, dosing such a reactant under reflux conditions potentially allows for removing the target species from the reactor, hence subtracting it from its further degradation. However, there exist also a number of processes that must be operated at temperature values lower than the normal boiling point of the low volatility product and for which vacuum conditions cannot be adopted, because of a number of process constraints. This prevents the possibility of taking advantage, from a safety point of view, of the aforementioned self-controlling feature of the processes operated under reflux conditions. The semibatch recycle reactor allows for achieving both a satisfactory process selectivity and productivity (strictly connected with the operating temperature range defined by the recipe) as well as the safer process conditions related to the reflux conditions thanks to its intrinsic possibility of operating even at atmospheric pressure the reaction vessel and the boiler at different temperature values.

Geothermal energy is a sustainable and clean energy source. Unfortunately, utilization of high-enthalpy geothermal systems is generally associated with emissions of gases like carbon dioxide (CO2), hydrogen sulfide (H2S), hydrogen (H2), nitrogen (N2), methane (CH4), and argon (Ar). The emission of some of these gases, particularly CO2, H2S and H2, is one of the main environmental concerns associated with the use of geothermal energy. The sequestration of these gases and their geological storage is the most diffuse viable option for reducing emissions. However, there is interesting technology, called AG2STM, that allows to convert H2S and CO2 into syngas. In this work, the match of this technology with geothermal power plant is analyzed as a new potential industrial route. The study is based on two different geothermal power plants located in Hellisheiði and Nesjavellirn (Iceland) that globally emit 61,800 t of CO2 and 28,200 t/y of H2S. The simulations provide some interesting results: (I) the total conversion of H2S that avoids its underground re-injection with the related environmental problem, (II) the reduction of CO2 emissions (about 8 %) and (III) the increasing of the global thermal energy produced with the same amount initial geothermal energy. The latter is due to the possibility to burn extra hydrogen coming from the AG2STM process. Finally, other advantages of this match are the production of an extra medium pressure steam and the possible reuse of the amount of H2 related to the geothermal plants emissions.

Polymeric dielectrics are employed extensively in the power transmission industry, thanks to their excellent properties; however, under normal operating conditions these materials tend to degrade and fail. In this study, samples of low-density polyethylene, polypropylene, polymethyl methacrylate, and polytetrafluorethylene were subjected to corona discharges under nitrogen and air atmospheres. The discharges introduced structural modifications over the polymer surface. From a chemical perspective, the alterations are analogous among the non-fluorinated polymers (i.e., polyethylene (PE), polypropylene (PP), and polymethyl methacrylate (PMMA)). A simulation of the corona discharge allowed the identification of highly reactive species in the proximity of the surface. The results are consistent with the degradation of insulating polymers in high-voltage applications due to internal partial discharges that ultimately lead to the breakdown of the material.

The photoreduction of CO2 is an intriguing process which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing a fully innovative pressurized photoreactor, allowing operation up to 20 bar and applied to improve the productivity of this very challenging process. The photoreduction of CO2 in the liquid phase was performed using commercial TiO2 (Evonink P25), TiO2 obtained by flame spray pyrolysis (FSP) and gold doped P25 (0.2 wt% Au-P25) in the presence of Na2SO3 as hole scavenger (HS). The different reaction parameters (catalyst concentration, pH and amount of HS) have been addressed. The products in liquid phase were mainly formic acid and formaldehyde. Moreover, for longer reaction time and with total consumption of HS, gas phase products formed (H2 and CO) after accumulation of significant number of organic compounds in the liquid phase, due to their consecutive photoreforming. Enhanced CO2 solubility in water was achieved by adding a base (pH = 12–14). In basic environment, CO2 formed carbonates which further reduced to formaldehyde and formic acid and consequently formed CO/CO2 + H2 in the gas phase through photoreforming. The deposition of small Au nanoparticles (3–5 nm) (NPs) onto TiO2 was found to quantitatively influence the products distribution and increase the selectivity towards gas phase products. Significant energy storage in form of different products has been achieved with respect to literature results.

The functionalization of multi-walled carbon nanotubes (MW-CNTs) was obtained by generating reactive perfluoropolyether (PFPE) radicals that can covalently bond to MW-CNTs’ surface. Branched and linear PFPE peroxides with equivalent molecular weights of 1275 and 1200 amu, respectively, have been thermally decomposed for the production of PFPE radicals. The functionalization with PFPE chains has changed the wettability of MW-CNTs, which switched their behavior from hydrophilic to super-hydrophobic. The low surface energy properties of PFPEs have been transferred to MW-CNTs surface and branched units with trifluoromethyl groups, CF3, have conferred higher hydrophobicity than linear units. Porosimetry discriminated the effects of PFPE functionalization on meso-porosity and macro-porosity. It has been observed that reactive sites located in MW-CNTs mesopores have been intensively functionalized by branched PFPE peroxide due to its low average molecular weight. Conductivity measurements at different applied pressures have showed that the covalent linkage of PFPE chains, branched as well as linear, weakly modified the electrical conductivity of MW-CNTs. The decomposed portions of PFPE residues, the PFPE chains bonded on carbon nanotubes, and the PFPE fluids obtained by homo-coupling side-reactions were evaluated by mass balances. PFPE-modified MW-CNTs have been characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), static contact angle (SCA), surface area, and porosity measurements.