Relevant Process Conditions Research Articles

Robust Imidazopyridinium Covalent Organic Framework as Efficient Iodine Capturing Materials in Gaseous and Aqueous Environment.

The development of a high-performing adsorbent that can capture both iodine vapor from volatile nuclear waste and traces of iodine species from water is an important challenge, especially in industrially relevant process conditions. This study introduces novel imidazopyridinium-based covalent organic frameworks (COFs) through post-modification of a picolinaldehyde-based imine COF. These COFs demonstrate excellent iodine adsorption capacity, adsorption kinetics, and a high stability/recyclability in both vapor and water phases. Notably, one imidazopyridinium COF exhibits gaseous iodine uptake of 21wt.% under dynamic adsorption conditions at 150°C and a relative humidity of 50%, surpassing the performance of the currently used silver-based zeolite adsorbents (Ag@MOR (17wt.%)). Additionally, the same imidazopyridinium COFs can efficiently remove iodine species at a low concentration from aqueous solution. Seawater containing triiodide ions treated under dynamic flow-through conditions resulted in decreased concentrations down to the ppb level. The adsorption mechanisms for iodine and polyiodide species are elucidated for the imine COF and imidazopyridinium COFs; involving halogen bonding, hydrogen bonding, and charge-transfer complexes.

Demonstrating the applicability of Raman spectroscopy for the characterization of hydrogen loading of bicyclic liquid organic hydrogen carriers (LOHCs) under process-relevant conditions

During hydrogenation and dehydrogenation reactions of liquid organic hydrogen carriers (LOHC), their thermophysical properties change significantly as a function of the degree of hydrogenation (DoH). Compared with conventional techniques, Raman spectroscopy offers a contactless methodology for online process monitoring without the need of sampling. This work demonstrates the application of Raman spectroscopy for the determination of the DoH under process-relevant conditions for LOHC systems based on diphenylmethane (DPM) and benzyltoluene (BT) up to 473 K. For the DPM-based system, a previous study is extended by examining the influence of process-like disturbances. For the BT-based system, a novel approach using indirect hard modeling of the unpolarized Raman spectra is applied, which results in strongly reduced uncertainties and insensitivity towards process-like disturbances, e.g. reaction by-products. For a corresponding testing set exhibiting a pronounced fluorescent background in the Raman spectra, the DoH is determined with an average absolute deviation of 0.0057.

Tuning the assembly of MgNiO2 nanoparticles-infused polysulfone membranes for efficient gas separation: The selectivity-permeability conundrum

The persistent surge in global energy demand, coupled with escalating environmental apprehensions, has underscored the imperative for adept and sustainable gas separation technologies. Mixed matrix membranes (MMMs) have surfaced as a promising avenue to confront these multifaceted challenges, synergistically harnessing the strengths of conventional polymeric membranes and nanoparticle reinforcements. In this work, MMMs have been tailored for gas separation applications by incorporating MgNiO2 nanoparticles as an additive into the polysulfone (PSf) matrix as they provide additional space (in the form of nanoscale voids) for gas diffusion, facilitating faster gas transport, promoting selective permeation of specific gases, and enhancing membrane stability, in addition to their versatility, ease of preparation, cost-effectiveness and high activity. The crystalline nature of MgNiO2 nanoparticles, as characterized by finely tuned grain sizes, has been validated by powder X-ray diffraction (XRD) analysis. Gas permeation experiments on the developed MMMs encompassing a diverse range of pure gases and gas mixtures have been performed. Among the different MMMs investigated, PSM1 with a composition of 100 mg MgNiO2 nanoparticles has yielded substantial enhancements in permeability and selectivity. The PSM1 membrane exhibits remarkable permeance of 56.9 for H2, 16.3 for CH4, and 15 GPU for CO2, having ideal selectivity ratios of 3.5 and 3.8 for H2/CH4 and H2/CO2, respectively. Finally, this work provides new directions for improving the trade of relationship between the selectivity and permeability of gas mixtures under relevant process conditions.

Study on pyrolysis characteristics, kinetics and thermodynamics of waste tires catalytic pyrolysis with low-cost catalysts

As a non-biodegradable solid waste, waste tires (WTs) have adverse effects on the ecological environment and human health. Waste tires are a good source of energy. In order to reduce the energy consumption of waste tires pyrolysis, this paper explores the influence of three low-cost catalysts on the catalytic effect of waste tires. The results of thermogravimetric experiments show that the use of spent FCC catalyst (FCC), red mud (Rm) and fly ash (Fa) during pyrolysis is beneficial to reducing the initial pyrolysis temperature of WTs. The kinetic calculation results show that compared with the direct pyrolysis of WTs, the average activation energy of WTs catalyzed by red mud and fly ash is reduced by about 9.5 kJ/mol and 7.8 kJ/mol, respectively. The average pre-exponential factor (lnA) decreased by about 1.3 min−1 and 1.4 min−1, respectively. The thermodynamic calculation results show that the endothermic reaction occurs in both the pyrolysis and catalytic pyrolysis of WTs, and the pyrolysis process cannot be carried out spontaneously. The pyrolysis reaction process of waste tires can be characterized by the combination of kinetics and thermodynamics, which provides parameters for determining the relevant process conditions for the industrialization of catalytic pyrolysis of waste tires.

Modulation of hen egg white protein techno-functionality by amyloid formation

Hen egg white protein (EWP) is an ingredient in many food products. EWP containing amyloid-like fibrils (ALFs) can be prepared under food processing relevant conditions and have specific techno-functional properties which advantageously can be exploited in specific food products. Here, we investigated whether combinations of heating and NaCl addition or trypsin treatment improve EWP fibrillation and gel properties. Heating (75 °C, 150 min) control 0.2% EWP solutions resulted in limited fibrillation unless they also contained 150 mM NaCl, in which case increased levels of curly ALFs were observed. When similarly heated control EWP solutions were submitted to trypsin treatment (37 °C, 24 h, 150 rpm), both straight and curly ALFs were formed. Gels [5.0%–6.0% (w/v) EWP] prepared by heating (75 °C, 150 min) of 150 mM NaCl containing dispersions or by similar heating without NaCl addition but with trypsin treatment contained ALFs of similar morphology but shorter than those in control EWP solutions. Increased levels of curly or of both straight and curly ALFs in NaCl containing gels or gels prepared with trypsin treatment, respectively, resulted in higher EWP gel stiffness than when the EWP gels were prepared in water. While the presence of straight ALFs in trypsin-derived EWP gels resulted in fast gel breakdown, the presence of both curly and straight ALFs reduced the amount of EWP needed for gel formation. The level and morphology of EWP ALFs can thus be modulated by specific food relevant processing and the resultant ALFs have specific gelling properties.

Experimental assessments of pyrolytic and fluid-dynamic interactions between pretreated residual biomasses and fluidized beds made up of oxygen carriers for chemical looping gasification

Oxygen carriers (OCs) and wheat straw pellets (raw or pretreated by combinations of torrefaction, CaCO3-addition, water-washing) were experimentally investigated for Chemical Looping Gasification (CLG) in the Horizon2020 project CLARA (Chemical Looping gAsification foR sustAinable production of biofuels, grant agreement n.817841). Laboratory-scale experiments included: (i) pellet devolatilizations (700 °C-900 °C) in bubbling fluidized beds made of OCs or sand; (ii) study of pressure fluctuations within OC fluidized beds (700–1000 °C) containing 10 vol% of ashes from investigated pellets, to assess OC/ash interactions and fluidization quality. Those two campaigns – performed at relevant process conditions for CLG – allowed straightforwardly screening and selecting the most eligible biomasses and OCs for future CLG demonstrations in fluidized beds at higher scales. Gas yield, H2/CO molar ratio, and carbon conversion increased as the devolatilization temperature increased from 700 °C to 900°C. Untreated and pretreated wheat straw pellets showed different pyrolytic behaviors. Analyses of pressure fluctuations and characterizations of spent beds (scanning electron microscopy, particle size distribution) suggested that biomass pretreatments limit agglomeration phenomena, depending on OCs nature (e.g., mechanical strength, composition). Ilmenite was the most mechanically and chemically stable OC. Among investigated materials, pretreated wheat straw pellets and ilmenite emerged as the most promising for future CLG demonstrations.

Standardized method for mechanistic modeling of multimodal anion exchange chromatography in flow through operation

Multimodal chromatography offers an increased selectivity compared to unimodal chromatographic methods and is often employed for challenging separation tasks in industrial downstream processing (DSP). Unfortunately, the implementation of multimodal polishing into a generic downstream platform can be hampered by non-robust platform conditions leading to a time and cost intensive process development. Mechanistic modeling can assist experimental process development but readily applicable and easy to calibrate multimodal chromatography models are lacking. In this work, we present a mechanistic modeling aided approach that paves the way for an accelerated development of anionic mixed-mode chromatography (MMC) for biopharmaceutical purification. A modified multimodal isotherm model was calibrated using only three chromatographic experiments and was employed in the retention prediction of four antibody formats including a Fab, a bispecific, as well as an IgG1 and IgG4 antibody subtype at pH 5.0 and 6.0. The chromatographic experiments were conducted using the anionic mixed-mode resin Capto adhere at industrial relevant process conditions to enable flow through purification. An existing multimodal isotherm model was reduced to hydrophobic interactions in the linear range of the adsorption isotherm and successfully employed in the simulation of six chromatographic experiments per molecule in concert with the transport dispersive model (TDM). The model reduction to only three parameters did prevent structural parameter non-identifiability and enabled an analytical isotherm parameter determination that was further refined by incorporation of size exclusion effects of the selected multimodal resin. During the model calibration, three linear salt gradient elution experiments were performed for each molecule followed by an isotherm parameter uncertainty assessment. Lastly, each model was validated with a set of step and isocratic elution experiments. This standardized modeling approach facilitates the implementation of multimodal chromatography as a key unit operation for the biopharmaceutical downstream platform, while increasing the mechanistic insight to the multimodal adsorption behavior of complex biologics.

Effect of industrial process conditions of fava bean (Vicia faba L.) concentrates on physico-chemical and functional properties

Fava bean (Vicia faba L.) is a promising source of proteins and has a potential in industrial food applications. Processing of fava ingredients modifies proteins and their functional properties. This study established the complexity of the relationship between fava protein-associated reactions (protein hydrolysis and aggregation), physico-chemical properties (electric charge, solubility, and intrinsic fluorescence, thermal integrity) and functional properties (foam and emulsion). For this study, an air-classified fava protein concentrate (65% w/w protein d.b.) was processed using pH (2, 4, 6.4 and 11), temperature (55, 75 and 95 °C) and duration of treatment (30 and 360 min) to produce 36 modified fava concentrates. Processing resulted in protein hydrolysis at pH < 4, and protein aggregation at pH ≥ 6.4 at temperatures above 75 °C, which influenced foaming and emulsification distinctly owing to the differences in their stabilizing mechanisms. Despite these modifications, their physico-chemical and functional properties were primarily governed by the beverage application pH. The surprising interplay shown between properties encourages the need to dive further into the different protein/non-protein reaction and interactions that can occur in fava concentrate. Industrial relevanceThe functionalities of fava bean protein-rich ingredients were investigated in industrial beverage application systems (pH 4 and 7) after industrial relevant process conditions (pH: 2, 4, 6.4 and 11; temperature: 55, 75 and 95 °C, treatment duration: 30 and 360 min). Foam capacity (>100%) was very high for all ingredients at both pH applications (acidic or pH 4, and neutral or pH 7), while the foam stability changed according to the application pH. So-called foam-breakers were discovered in acidic application, while all ingredients maintained high stability in neutral applications. A similar instability was found for emulsification, since emulsion made with all ingredients in acidic application creamed immediately after production. Emulsions in neutral applications were homogenous with all ingredients, thus, emulsion capacities were equivalent to each other, but the storage stability was affected by the ingredient processing pH.

Radioiodine sorbent selection criteria.

Methods for preventing radioiodine from entering the environment are needed in processes related to nuclear energy and medical isotope production. The development and performance of many different types of sorbents to capture iodine have been reported on for decades; however, there is yet to be a concise overview on the important parameters that should be considered when selecting a material for chemically capturing radioiodine. This paper summarizes several criteria that should be considered when selecting candidate sorbents for implementation into real-world systems. The list of selection criteria discussed are 1) optimal capture performance, 2) kinetics of adsorption, 3) performance under relevant process conditions, 4) properties of the substrate that supports the getter, and 5) environmental stability and disposition pathways for iodine-loaded materials.

Practically applicable water oxidation electrodes from 3D-printed Ti6Al4V scaffolds with surface nanostructuration and iridium catalyst coating

This study establishes the applicability of 3D printing (additive manufacturing) towards the generation of titanium alloy scaffolds for water oxidation electrodes. The scaffolds can be subsequently nanostructured by electrochemical anodization to enhance their surface area and coated with iridium as the electrocatalyst. We focus on the characterization of the functional electrodes in process-relevant conditions (1 M H2SO4, 60 ∘C, stirring) in terms of their performance and stability in a holistic manner. Various preparative conditions yield various patterns of performance and stability, as quantified by overpotentials η10 in steady-state electrolyses, maximum current densities jmax in dynamic voltammetry, surface roughness rf, and by overpotential increase, iridium loss, and jmax decrease after 100 h of operation, on the other hand. In other words, the system is highly flexible and can be adapted to specific constraints depending on the application chosen.

Intrinsic kinetics of CO2 methanation on low-loaded Ni/Al2O3 catalyst: Mechanism, model discrimination and parameter estimation

The mechanism and kinetic of CO2 methanation reaction of 9.5 % Ni/Al2O3 catalyst is analysed under a wide range of operating conditions. Once the catalyst activity is stabilized, the influence of temperature, total pressure and space velocity is studied for kinetic characterisation. A data set comprising of 153 experimental runs has been used to develop a kinetic model capable to accurately predict the reaction rate. Ni/Al2O3 catalyst shows an apparent activation energy of 80.1 kJ mol−1 in CO2 hydrogenation. Data obtained under differential mode adjust quite precisely to a power-law model with H2O inhibition, with a water adsorption constant of 3.1 atm−1 and apparent orders of 0.24 and 0.27 for H2 and CO2, respectively. Based on DRIFTS results, we propose for the first time the H-assisted CO formation route, which is compared with the more conventionally reported carbonyl route, and describe the corresponding reaction rate LHHW equation, resulting in notable improvement for mean deviation (D) of 7.0 % in our model related to that based on the carbonyl route (D = 20.1 %) usually suggested for catalysts with higher Ni loads around 20 %. The H-assisted CO formation route considers the formate species decomposition into carbonyls via H-assisted CO formation mechanism and further carbonyls hydrogenation into CHO as the rate determining step. Thus, the LHHW mechanism, in which carbonyls as well as formate species participate in CO2 methanation, is capable to reflect the kinetics of lowly-loaded Ni/Al2O 3 catalyst with high accuracy under relevant process conditions (315−430 °C, 1−6 bar, H2 to CO2 molar ratios between 1–16 and, different reagents and products partial pressures).

The potential impact of an implementation of microalgae-based wastewater treatment on the energy balance of a municipal wastewater treatment plant in Central europe

Integration of a photobioreactor for WWT by microalgae is calculated as a future alternative for cost-efficient and environmentally-friendly nutrient removal for municipal WWTPs. High growth rates and higher biogas yields (compared to conventional sewage sludge) of algal biomass can significantly improve WWTP energy balances.This study focuses on temperate climate zones with changing seasons and discusses energy potential of microalgae-enhanced wastewater treatment for an existing WWTP (32,000 PE) in Central Germany. For WWTP-dimensioning and determination of energy-rich biomasses for anaerobic digestion and CHP, actual influent load data was used and calculation was carried out according to valid regulations. Algae growth figures are based on pilot-scale test series from Germany and correspond to the relevant climatic and local process conditions. Computed results show a shift in the energy balance from a current energy demand of 662,173kWh a-1 to an energy production of approx. 1,9MWhel. a-1 and 1 MWhth. a-1.

Development of a gamma irradiation loop to evaluate the performance of a EURO-GANEX process

A new irradiation loop design has been developed, which provides the ability to carry out radiolytic resistance studies of extraction systems simulating process relevant conditions in an easy and simple way. The step-by-step loop configuration permits an easy modification of settings and has a relative low volume requirement. This irradiation loop has been initially set up to test the main EURO-GANEX process steps: the lanthanide (Ln) and actinide (An) co-extraction followed by the transuranic (TRU) stripping. The performance and changes in the composition have been analyzed during the irradiation experiment by different techniques: gamma spectroscopy and ICP-MS for the extraction and corrosion behavior of the full system, and HPLC-MS and Raman spectroscopy to determine the degradation of the organic and aqueous solvents, respectively. The Ln and An co-extraction step and the corrosion that occurred during the first irradiation step revealed the favorable expected results according to literature. The effects of acidity changes occurred during the irradiation process, the presence of stainless corrosion products in solution as well as the new possible degradation compounds have been explored in the An stripping step. The results obtained demonstrate the importance of developing realistic irradiation experiments where different factors affecting the performance can be easily studied and isolated.

Analysis of hydrogen production potential from waste plastics by pyrolysis and in line oxidative steam reforming

A study was carried out on the valorization of different waste plastics (HDPE, PP, PS and PE), their mixtures and biomass/HDPE mixtures by means of pyrolysis and in line oxidative steam reforming. A thermodynamic equilibrium simulation was used for determining steam reforming data, whereas previous experimental results were considered for setting the pyrolysis volatile stream composition. The adequacy of this simulation tool was validated using experimental results obtained in the pyrolysis and in line steam reforming of different plastics. The effect the most relevant process conditions, i.e., temperature, steam/plastic ratio and equivalence ratio, have on H2 production and reaction enthalpy was evaluated. Moreover, the most suitable conditions for the oxidative steam reforming of plastics of different nature and their mixtures were determined. The results obtained are evidence of the potential interest of this novel valorization route, as H2 productions of up to 25 wt% were obtained operating under autothermal conditions.

The efficiency of scrap Cu and Al current collector materials as reductants in LIB waste leaching

This current study addresses the role of copper and aluminum - typical major components of current collector scrap from battery manufacturing plants - in the leaching of pre-treated LiCoO2-rich battery waste concentrate at industrially relevant process conditions (T = 60 °C, [H2SO4] = 2 M, S/L = 200 g/L). An empirical model has been constructed which demonstrates that the effects of both copper and aluminum are significant. Both elements have independent and linear impacts on cobalt extraction and acid consumption. The model predicts that either 11 g of copper (0.75 Cu/Co, mol/mol), 4.8 g of aluminum (0.7 Al/Co, mol/mol) or a combination of both are required for full cobalt extraction from 100 g of sieved industrial battery waste concentrate. Aluminum was shown to influence cobalt leaching although it was less effective (47%) when compared to copper (66%) in terms of current efficiency due to associated side reactions, such as excess H2 formation. Aluminum has several possible reaction routes for LiCoO2 reduction; in parallel or in series via H2 formation, Cu2+ cementation and/or Fe3+ reduction, whereas copper acts solely through Fe3+ reduction. These results indicate that by using copper scrap, in preference to the more typical hydrogen peroxide, the CO2 footprint of the battery leaching stage could be decreased by at least 500 kg of CO2 per ton of recycled cobalt. In contrast, the use of aluminum, although promising, is less attractive due to the challenges related to its removal during subsequent solution purification.

Inside Back Cover: Microfabrication Enables Quantification of Interfacial Activity in Thermal Catalysis (Small Methods 5/2021)

In article number 2001231, Pérez-Ramírez and co-workers devise a method using microfabricated model catalysts and a custom-designed reactor to decouple the contribution of metal-oxide interfaces in Cu-ZnO for methanol synthesis via CO and CO2 hydrogenation under process-relevant conditions.

NOx Reduction Using Pilot-Scale SCR Under Oxyfuel Conditions

This paper presents a comprehensive experimental study of selective catalytic reduction (SCR) of nitrogen oxides formed in the oxyfuel combustion of lignite coal in a 500 kWth pilot-scale bubbling fluidized bed (BFB) boiler using the V2O5 over TiO2 honeycomb catalyst and the ammonia as the reducing agent. The study also compares the performance of the SCR between oxyfuel and air combustion modes. The SCR unit is placed in the tail-end position of the flue gas processing scheme after the cyclone particle separator. Experiments were realized both in air- and oxyfuel combustion regime, evaluating the impact of relevant process conditions on the NOx reduction. The dependence of the NOx reduction efficiency on the catalyst temperature and on the normalized stoichiometric ratio (NSR) of the reducing agent molar flow to the molar flow of NOx were studied. The efficiency of the NOx reduction was evaluated based on the NOx concentration measured simultaneously before and after the SCR unit. In the off-gas, the concentration of unreacted reducing agent (ammonia slip) was measured as well. For evaluation of real NSR, ammonia and flue gas flow rates were measured during each experiment. The catalyst temperature was regulated within the experiments in the range of 260 to 300 °C and the NSR was chosen in the range of 0 to 1.2. From this experimental setup, the correlations of the NOx reduction efficiency related to the different NSR and catalyst temperature were evaluated. The results show the fundamental information about the differences between air and oxyfuel conditions in a real combustion environment. In general, the NOx conversion efficiency was significantly higher during air combustion. In order to get similar results of maximum NOx conversion as reached during air combustion, it was necessary to increase NSR up to 1.8 and more, however at the cost of significantly increased ammonia slip. Although the SCR performance is lower in oxyfuel combustion, it was possible to decrease NOX under 100 ppmv with NSR about 1 and without any significant ammonia slip, which is important prior to further CO2 treatment.

Microfabrication Enables Quantification of Interfacial Activity in Thermal Catalysis.

A myriad of heterogeneous catalysts comprises multiple phases that need to be precisely structured to exert their maximal contribution to performance through electronic and structural interactions at their peripheries. In view of the nanometric, tridimensional, and anisotropic nature of these materials, a quantification of the interface and the impact of catalytic sites located there on the global performance is a highly challenging task. Consequently, the true origin of catalysis often remains subject of debate even for widely studied materials. Herein, an integrated strategy based on microfabricated catalysts and a custom-designed reactor is introduced for determining interfacial contributions upon catalytic activity assessment under process-relevant conditions, which can be easily implemented in the common catalysis research infrastructure and will accelerate the rational design of multicomponent heterogeneous catalysts for diverse applications. The method is validated by studying the high-pressure continuous-flow hydrogenation of CO and CO2 over Cu-ZnO catalysts, revealing linear correlations between the methanol formation rate and the interface between the metal and the oxide. Characterization of fresh and used materials points to the model catalyst preparation as the current challenge of the methodology that can be addressed through further development of nanotechnological tools.

A very boring 120 h: 15 million tablets under a continuous state of control

The aim of this study is to show the robustness of a commercial direct compression system running continuously under relevant process conditions for over 120 h. The study will apply a representative commercial control strategy including real time monitoring of process parameters, rejection of OOS material, use of in-line NIR prediction for blend potency monitoring, application of mathematical RTD modelling for real-time prediction of product potency, and tablet concentration prediction by tablet NIR.The study showed that the process can produce in specification product robustly over significant operating times. Across 122 h of actual run time (including pauses) the process manufactured over 15 million tablets to give a product yield of 99.2%. Whilst the purpose of this study was to evaluate the process for over 120 h, this process is not limited to running longer periods of time given the performance of the equipment and the control strategy.

Properties, performance and stability of iridium-coated water oxidation electrodes based on anodized titanium felts

Holistic performance characterization: not only one performance parameter, but short-term electrocatalytic proficiency in process relevant conditions combined with long-term stability.