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The production of biologic products by fermentation has grown significantly within the last decade and continues to grow further. Large volumes of wastewater are produced by anaerobic digesters, which contain dissolved CO2 and NH3 in addition to other compounds, making it difficult to treat in an economic way. In this work, we have developed a novel process solution of an NH3 recovery process that first strips off CO2 from the wastewater, then produces a concentrated NH3 solution. This solution not only avoids both precipitation of solids and the use of caustic, but also allows for adjustments of the composition of the concentrated NH3 solution, thus enabling its re-utilization in different applications. Based on this development, pilot plant tests were conducted with the aim of proving process feasibility. Then, a rigorous process optimization was carried out, where the optimal set of process parameters were determined. The results suggest that the optimal operation not only depends on the operating conditions, but also on the process configuration depending on the input and storage conditions; four different configurations were developed, which enable the selection of an optimal design that minimizes both the operating costs via external heat demand, and capital costs via process complexity., Chemical Engineering Research and Design, 193, ISSN:0263-8762, ISSN:1744-3563

This work presents a generalized framework to assess the accuracy of methods to estimate primary and secondary nucleation rates from experimental data. The crystallization process of a well-studied model compound was simulated by means of a novel stochastic modeling methodology. Nucleation rates were estimated from the simulated data through multiple methods and were compared with the true values. For primary nucleation, no method considered in this work was able to estimate the rates accurately under general conditions. Two deterministic methods that are widely used in the literature were shown to overpredict rates in the presence of secondary nucleation. This behavior is shared by all methods that extract rates from deterministic process attributes, as they are insensitive to primary nucleation if secondary nucleation is sufficiently fast. Two stochastic methods were found to be accurate independent of whether secondary nucleation is present, but they underestimated rates in the case where a large number of primary nuclei are formed. We hence proposed a criterion to probe the accuracy of stochastic methods for arbitrary data sets, thus providing the theoretical foundations required for their rational use. Finally, we showed how both primary and secondary nucleation rates can be inferred from the same set of detection time data by combining deterministic and stochastic considerations., Crystal Growth & Design, 23 (2), ISSN:1528-7483, ISSN:1528-7505

The chemical industry is responsible for about 5% of global CO2 emissions and is key to achieving net-zero targets. Decarbonizing this industry, nevertheless, faces particular challenges given the widespread use of carbon-rich raw materials, the need for high-temperature heat, and the complex global value chains. Multiple technology routes are now available for producing chemicals with net-zero CO2 emissions based on biomass, recycling, and carbon capture, utilization, and storage. However, the extent to which these routes are viable with respect to local availability of energy and natural resources remains unclear. In this review, we compare net-zero routes by quantifying their energy, land, and water requirements and the corresponding induced resource scarcity at the country level and further discuss the technical and environmental viability of a net-zero chemical industry. We find that a net-zero chemical industry will require location-specific integrated solutions that combine net-zero routes with circular approaches and demand-side measures and might result in a reshaping of the global chemicals trade., One Earth, 6 (6), ISSN:2590-3322

This article addresses the application of the indirect mineral carbonation process to recycled concrete aggregates (RCA). In such a process, calcium is first leached from the RCA feedstock into an aqueous ammonium nitrate solution and then it is carbonated to precipitate calcium carbonate. The calcium leaching step is modeled in this contribution, whereas it was investigated experimentally in part 1 of this series, where the focus was more on thermodynamic aspects than on kinetics. In this part 2 paper, kinetics aspects are also included by modeling them using two different approaches. In the first approach, the reaction-diffusion model is implemented, accounting for the congruent dissolution of the calcium hydroxide phase and the incongruent dissolution of the calcium silicate hydrate components of concrete fines. In the second approach, a double-shrinking-core model is used, which for the sake of simplicity assumes congruent dissolution of calcium silicate hydrates as well, infinitely fast reaction/dissolution kinetics, and pseudo-steady-state diffusion. The model parameters have been either determined through targeted experiments or estimated by fitting measurements obtained in experiments with two different materials, both in the size range of up to a diameter of 4 mm. Both models exhibit satisfactory accuracy in describing the experimental data; particularly for particles larger than about 0.1 mm in diameter, the two models calculate a nearly identical evolution of the calcium concentration in solution. The simplifications of the double-shrinking-core model lead to a loss of resolution in characterizing the evolution of leaching inside the particles, whereas they enable faster computations. The latter feature makes such a model a convenient tool for studying process performance, namely, productivity, calcium recovery, and solvent efficiency, through parametric analysis; this has been demonstrated as reported in the last part of the article., Industrial & Engineering Chemistry Research, 62 (6), ISSN:1520-5045, ISSN:0888-5885

Membrane-based gas separation processes are currently being implemented at different scales for several industrial applications. The optimal design of such processes, which is of key importance for their large-scale commercial deployment, has been extensively studied through parametric analyses and optimisation procedures. Nevertheless, the applicability of such design methodologies is generally limited by the large computational time and effort they require. In this work, surrogate models based on artificial neural networks are developed to circumvent the lengthy optimisation of a one-stage and two-stage cascade membrane-based gas separation process. In 200 ms, the surrogate model generates a Pareto front that describes the optimal trade-off between the process specific electricity consumption and productivity based on given input data, i.e., membrane material properties, feed composition and separation target. Whereas the surrogate model is applicable to any binary gas mixture, here its features are illustrated by creating process performance maps for post-combustion CO2 capture. Such maps provide valuable insights on: (i) attainable gas separation regions in term of CO2 recovery and CO2 purity, and (ii) the impact of membrane material, feed composition and separation target on the Pareto fronts and the optimal operating conditions., International Journal of Greenhouse Gas Control, 122, ISSN:1750-5836, ISSN:1878-0148

Characterization of particle size and shape is central to the study of particulate matter in its broadest sense. Whilst 1D characterization defines the state of the art, the development of 2D and 3D characterization methods has attracted increasing attention, due to a common need to measure particle shape alongside size. Herein, ensembles of micrometer-sized cuboidal particles are studied, for which reliable sizing techniques are currently missing. Such particles must be characterized using three orthogonal dimensions to completely describe their size and shape. To this end, the utility of an online and in-flow multiprojection imaging tool coupled with machine learning is experimentally assessed. Central to this activity, a methodology is outlined to produce micrometer-sized, non-spherical analytical standards. Such analytical standards are fabricated using photolithography, and consist of monodisperse micro-cuboidal particles of user-defined size and shape. The aforementioned activities are addressed through an experimental framework that fabricates analytical standards and subsequently uses them to validate the performance of our multiprojection imaging tool. Significantly, it is shown that the same set of data collected for particle sizing can also be used to estimate particle orientation in flow, thus defining a rapid and robust protocol to investigate the behavior of dilute particle-laden flows., Small Methods, 7 (1), ISSN:2366-9608

The sealing characteristics of the geological formation located above a CO2 storage reservoir, the so-called caprock, are essential to ensure efficient geological carbon storage. In case CO2 were to leak through the caprock, temporal changes in fluid geochemistry can reveal fundamental information on migration mechanisms and induced fuid-rock interactions. Here, we present the results from a unique in-situ injection experiment, where CO2-enriched fluid was continuously injected in a faulted caprock analogue. Results show that the CO2 migration follows complex path- ways within the fault structure. The joint analysis of noble gases, ion concentrations and carbon isotopes allow us to quantify mixing between injected CO2-enriched fluid and resident formation water and to describe the temporal evolution of water-rock interaction processes. The results presented here are a crucial complement to the geophysical monitoring at the fracture scale highlighting a unique migration of CO2 in fault zones.

This study investigates the optimal design of carbon capture, transport and storage (CCTS) supply chains for decarbonizing industrial emitters. It builds upon previous analyses, which determine the cost-optimal design of CCTS supply chains while complying with specified emissions reduction scenarios, and determines optimal designs in terms of minimum cost and maximum resilience. The resilience of a supply chain is defined as its ability to permanently store the captured CO2 during the time horizon of interest, and it is quantified in terms of expected amount of carbon not stored under a fixed number of possible simultaneous failures. A mixed-integer linear program is developed to design CCTS supply chains that ensure a specified level of resilience while minimizing total system costs and CO2 emissions. The model is illustrated by determining the optimal decarbonization strategy in terms of costs and level of resilience for the Swiss waste-to-energy sector from 2025 to 2050. Overall, resilience is achieved with a cost increase with respect to the cost-optimal solution ranging from about 5% (backup truck connections to minimize the cost of the supply chain) to about 70% (backup pipeline connections to minimize the emissions of the supply chain) when the storage site is in the North Sea. When the storage site is available in Switzerland, the cost increase is much reduced and ranges from about 1% to 10% with respect to the cost-optimal solution., International Journal of Greenhouse Gas Control, 121, ISSN:1750-5836, ISSN:1878-0148

Solid-state deracemization via temperature cycles is a promising technique that combines crystallization and racemization in the same batch process to attain enantiomer purification. This method is particularly attractive because the target enantiomer can be isolated with a 100% yield, and a large number of operating parameters can be adjusted to do this effectively. However, this implies that several choices need to be made to design the process for a new compound. In this work, we provide a solution to this dilemma by suggesting a simplified model-free design approach based on a single dimensionless parameter, that is, the dissolution factor, that represents the cycle capacity. This quantity is obtained from a novel rescaling of the model equations proposed in previous work and acts as a handy design parameter because it only depends on the operating conditions, such as the suspension density, the enantiomeric excess, and the difference in solubility between high and low temperatures in the cycle. With extensive modeling studies, supported by experimental results, we demonstrate the primary and general effect of the dissolution factor on the deracemization process and thus its relevance for the process design. Through both experiments and simulations, we rationalize and evaluate the process performance when periodic and non-periodic temperature cycles are applied to the deracemization of virtual and real compounds with different properties, that is, growth rate and solubility. Based on the approach proposed here, we clarify how the combined effect of more operating conditions can be exploited to obtain quasi-optimal process performance, which results superior when deracemization via periodic temperature cycles is performed., Organic Process Research & Development, 25 (11), ISSN:1083-6160, ISSN:1520-586X

With the aim of removing fine particles from a suspension obtained by crystallization, a selective dissolution process featuring a hydrocyclone is compared against a well-established partial dissolution process with a dedicated experimental campaign, which complements an earlier theoretical study. For this purpose, 3D printed hydrocyclones, solid- liquid separation devices, are studied in detail and successfully operated under conditions viable at the laboratory scale. A model due to Braun is fitted to the experimental results and validated using a cross validation strategy, thus providing a valuable tool for process simulation. The experimental campaign is designed to comparatively assess the efficacy and efficiency of the two processes under analysis as a function of their respective operating conditions, finally demonstrating the superior performance of the selective dissolution process. In particular, it is shown that while in a standard partial dissolution process 20-40% of the suspended mass has to be dissolved to remove a reasonable amount of fines, the proposed process reaches the same goal by dissolving as little as 3-10%., Industrial & Engineering Chemistry Research, 60 (43), ISSN:1520-5045, ISSN:0888-5885

The aviation sector must substantially reduce its climate impacts to reach net-zero goals. Such a reduction, however, must not be limited to flight CO2 emissions, since such a narrow focus leaves up to 80% of climate impacts unaccounted for – especially with further growth of air traffic. This study – based on rigorous life-cycle assessment combined with a time-dependent quantification of non-CO2 climate impacts – shows that both electricity-based synthetic jet fuels and compensating climate impacts via direct air carbon capture and storage (DACCS) can enable climate-neutral aviation. However, with a continuous increase in air traffic, synthetic jet fuels produced with electricity from renewables would exert excessive pressure on economic and natural resources, while compensation via DACCS would require massive CO2 storage volumes and prolong dependence on fossil fuels. Hence, the idea of a climate-neutral aviation will fly only if air traffic decreases to reduce the scale of climate impacts to mitigate.

A rliqsolution process featuring a hydrocyclone for the selective removal of fine crystals, i.e., an operation analyzed through modeling and experiments in earlier studies, is implemented into a 3-stage cyclic crystallization process, which consists of repeated application of crystal growth, wet milling, and dissolution. For the selection of a hydrocyclone and of its operating conditions, experiments demonstrate that a mathematical model provides accurate estimates of the classification curve for different compounds and physical properties of the suspension, thus facilitating the process design. Two campaigns are conducted with two compounds, namely, gamma D-mannitol and beta L-glutamic acid, where the selective dissolution strategy is compared to standard partial dissolution in terms of the attributes of the final product powder obtained from the 3-stage process. Crystal size, crystal shape, flowability, and filterability are measured, and it is shown that they are greatly influenced by the dissolution stages. Most remarkably, in the case of gamma D-mannitol, the experimental evidence shows that selective dissolution enables the removal of a greater amount of fines for the same mass of crystals being dissolved, thus improving the productivity of the process, as well as the measured flow and filtration performance., Industrial & Engineering Chemistry Research, 61 (43), ISSN:1520-5045, ISSN:0888-5885

In this work, the dissolution step of the indirect mineral carbonation process was investigated; first, a process-relevant thermodynamic framework is introduced, and then, an extensive experimental campaign with aqueous ammonium nitrate (AN) as the solvent is presented. Steady-state experiments after 24 h of leaching under different solvent concentrations and cement dosing were studied, confirming the applicability of the developed thermodynamic framework and its mathematical description. Afterward, batch experiments were performed to study the kinetic leaching behavior from different particle sizes, at different temperatures, and under a variety of industrially relevant conditions. Smaller particles release more calcium faster than larger particles as their calcium content is higher, and they have more specific surface available and less intraparticle diffusion limitations. Between temperatures of 5 and 35 degrees C, a 20% increase in dissolution performance was observed, which is due to an increase in reaction kinetics and/or diffusivity. Experiments under industrially relevant conditions reveal that increasing both the AN concentration and the solid to liquid ratio increases the amount of calcium in solution but has contradicting effects on extraction efficiency. For the typical conditions of a solid to liquid ratio of 0.2 and an AN concentration of 0.5 M, about 32% of the available calcium was leached after 20 min, resulting in a calcium concentration of 0.065 M; thereafter, this leaching process slows down sharply. The knowledge developed in this work forms a solid foundation for future modeling and scaling up of the indirect mineral carbonation process., Industrial & Engineering Chemistry Research, 61 (41), ISSN:1520-5045, ISSN:0888-5885

We present a molecular dynamics simulation method for the computation of the solubility of organic crystals in solution. The solubility is calculated based on the equilibrium free energy difference between the solvated solute and its crystallized state at the crystal surface kink site. To efficiently sample the growth and dissolution process, we have carried out well-tempered metadynamics simulations with a collective variable that captures the slow degrees of freedom, namely, the solute diffusion to and adsorption at the kink site together with the desolvation of the kink site. Simulations were performed at different solution concentrations using constant chemical potential molecular dynamics, and the solubility was identified at the concentration at which the free energy values between the grown and dissolved kink states were equal. The effectiveness of this method is demonstrated by its success in reproducing the experimental trends of solubility of urea and naphthalene in a variety of solvents., Crystal Growth & Design, 21 (9), ISSN:1528-7483, ISSN:1528-7505

We combine molecular dynamics simulations with experiments to estimate solubilities of an organic salt in complex growth environments. We predict the solubility by simulations of the growth and dissolution of ions at the crystal surface kink sites at different solution concentrations. Thereby, the solubility is identified as the solution's salt concentration, where the energy of the ion pair dissolved in solution equals the energy of the ion pair crystallized at the kink sites. The simulation methodology is demonstrated for the case of anhydrous sodium acetate crystallized from various solvent- antisolvent mixtures. To validate the predicted solubilities, we have measured the solubilities of sodium acetate in-house, using an experimental setup and measurement protocol that guarantees moisture-free conditions, which is key for a hygroscopic compound like sodium acetate. We observe excellent agreement between the experimental and the computationally evaluated solubilities for sodium acetate in different solvent-antisolvent mixtures. Given the agreement and the rich data the simulations produce, we can use them to complement experimental tasks, which in turn will reduce time and capital in the design of complicated industrial crystallization processes of organic salts., Journal of Chemical Theory and Computation, 18 (8), ISSN:1549-9618, ISSN:1549-9626

Biopharmaceuticals commonly require freezing to ensure the stability of the active pharmaceutical ingredients (APIs). At commercial scale, freezing is typically carried out over the course of days in pallets comprising tens of thousands of vials. The selected process conditions have to ensure both complete freezing in all vials and a satisfactory manufacturing throughput. Current process design, however, is mainly experimental, since no mechanistic understanding of pallet freezing and its underlying phenomena has been achieved so far. Within this work, we derive a mechanistic modeling framework and compare the model predictions with engineering run data from the Janssen COVID-19 vaccine. The model qualitatively reproduced all observed trends and reveals that stochastic ice nucleation governs both process duration and batch heterogeneity. Knowledge on the ice nucleation kinetics of the formulation to be frozen thus is required to identify suitable freezing process conditions. The findings of this work pave the way towards a more rational design of pallet freezing, from which a plethora of frozen drug products may benefit. For this reason, we provide open source access to the model in the form of a python package (Deck et al., 2021)., International Journal of Pharmaceutics, 625, ISSN:0378-5173, ISSN:1873-3476, ISSN:0378 -5173

This work presents a novel optimization framework for the optimal design of carbon capture, transport, and storage supply chains in terms of installation, sizing and operation of carbon dioxide (CO2) capture and transport technologies. The optimal design problem is formulated as a mixed-integer linear program that minimizes the total costs of the supply chains while complying with different emissions reduction pathways over a deployment time horizon of 25 years. All design decisions are time-dependent and are taken with a yearly resolution. Whereas the model is general, here its features are illustrated by designing optimal supply chains to decarbonize the Swiss waste-to-energy sector, for various emission reduction pathways, when up to two storage sites are considered, namely one in the North Sea assumed to be already available and a hypothetical one in Switzerland assumed to be possibly available in the future. Findings show that, unless a domestic storage site becomes available soon, the transport cost is the greatest contribution to the overall costs, followed by the capture cost, while the storage cost plays only a minor role. Pipelines are the most cost-effective mode of transport for large volumes of transported CO2, especially when considering multi-year time horizons for the planning of the supply chains. Ship and barge connections are competitive with pipeline connections, whereas rail and truck connections are cost-optimal only when considering shortsighted time horizons or small volumes of CO2 transported., International Journal of Greenhouse Gas Control, 117, ISSN:1750-5836, ISSN:1878-0148

We address the purification of the target enantiomer of a chiral compound from its racemic mixture, through simulated moving bed (SMB) chromatography either as a standalone or combined with the recycle and racemization of the undesired enantiomer. We carry out a comparative assessment of the two processes with focus on the role of the racemization kinetics, on the effect of the selectivity of the chiral stationary phase, and of the upstream symmetric synthesis of the racemate. The analysis is general thanks to the methods adopted for the optimal design of the integrated process (with racemization) and for the sizing of the SMB unit, as well as for the use of the four generalized Langmuir adsorption isotherms. In this way, we determine quantitative criteria that show that the standalone SMB process outperforms the integrated process when the performance of the racemization catalyst or the chiral stationary phase is poor and the racemic feed is inexpensive., Industrial & Engineering Chemistry Research, 60 (29), ISSN:1520-5045, ISSN:0888-5885

In this work, we examine the chromatographic purification of the chiral amide N-(2-methyl-benzylidene)-phenylglycine amide (NMPA). Specifically, we find that its adsorption behavior on an AY polysaccharidic chiral stationary phase (amylose tris(5-chloro-2-methylphenylcarbamate)), with acetonitrile as mobile phase, follows an uncommon type-1 mixed Langmuir isotherm. Moreover, we measure the racemization rate of NMPA when polymer-supported 1,8-diazabicycloundec-7-ene (DBU) is used as a catalyst in a fixed-bed reactor. We also determine the system's solid-liquid equilibria at different temperatures. This characterization is necessary for the design of an integrated process where simulated moving bed (SMB) chromatography is combined with racemization for the recycle of the undesired enantiomer. On the basis of the physicochemical properties above, three-column intermittent SMB (3C-ISMB) experiments were run at different concentrations and compositions to prove that an enantiopure product can be obtained when the separation is operated at high feed concentrations (nonlinear chromatographic conditions) in the case not only of a racemic feed but also of nonracemic feeds, which are relevant for the integrated process when racemization is slow, and thus incomplete., Industrial & Engineering Chemistry Research, 60 (29), ISSN:1520-5045, ISSN:0888-5885

The density and the viscosity of aqueous (NH3 + CO2) solutions have been measured at atmospheric pressure over a temperature range of 278 to 318 K and apparent concentrations of solute between 4 and 10 molNH3 kgH2O-1 for NH3 and between 1 and 5.2 mol CO2 kgH2O-1 for CO2. Solute loss from the aqueous solution associated with the high equilibrium partial pressure of NH3 and of CO2 has been limited by devices and protocols developed ad-hoc for sample preparation and density and viscosity measurement. Solid or vapor formation out of the initial liquid mixture has been avoided by means of a thermodynamic model-driven design of experiments. The experimental values gathered in this work have been used to obtain empirical models of density and viscosity, as a function of the apparent concentration of solutes, that is, NH3 and CO2, and temperature, that are able to reproduce the experimental values in all cases with deviations below 1.1% for density and below 9.4% for viscosity. While it is the first time that, to our knowledge, experimental viscosity data of aqueous ammonia solutions loaded with CO2 are added to the literature, the density model developed in this work is also able to reproduce experimental density data from literature with deviations below 1.5%, even outside the boundaries of the experimental conditions considered in this work., Journal of Chemical & Engineering Data, 66 (4), ISSN:0021-9568, ISSN:1520-5134

A large number of prospective climate scenarios rely on Carbon Dioxide Removal (CDR) technologies to limit global warming below 2 °C. To date, however, a comprehensive understanding of the overall life-cycle environmental impacts of CDR technologies is missing. We present a critical review on conducted Life Cycle Assessments (LCAs) of a comprehensive set of CDR technologies: afforestation and reforestation, biochar, soil carbon sequestration, enhanced weathering, ocean fertilisation, bioenergy with carbon capture and storage, and direct air carbon capture and storage. One of the key observations is that emissions avoided due to substitution of certain processes (due to system expansion in LCA) can be easily misinterpreted as negative emissions, i.e. as carbon removal from the atmosphere. Based on the observed inconsistencies and shortcomings, we recommend to interpret available CDR LCA results with caution. To improve the understanding of environmental implications of CDR deployment, we recommend (1) to conduct LCAs with multiple environmental impact categories, (2) to consider the temporal aspect of emissions in biomass-related CDR technologies, (3) to focus on so far overlooked CDR technologies, (4) to be as transparent as possible regarding methodological choices, (5) to capture environmental side-effects, and (6) to distinguish between ‘avoided emissions’ and ‘negative emissions’ – only negative emissions correspond to permanent removal from the atmosphere. We conclude that more comprehensive and rigorous LCAs are needed to help inform the design of CDR technology portfolios and to aid in anticipatory governance.

Bioenergy with Carbon Capture and Storage (BECCS) is a Carbon Dioxide Removal (CDR) technology that will likely be necessary to reach global net-zero carbon dioxide emission goals. In order to assess the European BECCS potential, we quantify at 1 km resolution the technical potential for biogenic CDR considering seven different BECCS configurations that do not require purpose-grown bio-energy plantations. Combining process engineering with geospatial assessment, we find that up to 5% of 2018 European emissions, or about 200 million tons CO2 per year, could be mitigated with biogenic CDR from BECCS. Such potential is at the lower bound of the range of projected CDR needs for Europe. Two thirds of this potential is from existing point sources (pulp and paper, biomass co-fired, waste-to-energy, and wastewater treatment facilities), while one third is from distributed sources (crop residues, organic food waste, and livestock manure). From a geopolitical perspective, only a few European countries reach or exceed their CDR needs via BECCS. Those countries, which will not be able to reach carbon-neutrality with domestic biomass resources, will likely need to resort to other CDR strategies or import biomass from abroad. From a geographic perspective, distances from emission sources and storage sites are rather unfavourably distributed. Based on our quantitative assessment we conclude that: (1) tapping into the whole 200 million tons CO2 per year will be challenging because of the unfavourable source–sink distance distribution; (2) there is a need for more and better distributed prospective CO2 storage sites in Europe; and (3) the mobilization of these large amounts of CO2 will require the realization of a Europe-wide CO2 transportation network.

The use of biomass as a resource for hydrogen production can contribute to the transition towards carbon neutral or carbon negative energy systems. This paper offers a comprehensive investigation of the technical performance and life cycle environmental footprint of three gasification technologies for H2 production, using dry biomass (wood) as input. These are compared with H2 production from reforming of natural gas or biomethane and electrolysis as presented in our previous work. This is followed by an evaluation of the use of H2 as fuel for passenger cars and trucks. The quantity of biomass required for the production of 1 MW H2 is calculated with an integrated process simulation approach on the basis of Aspen Plus simulations and real-plant literature data. We observe that all the technologies analysed provide negative CO2 emissions when coupled with CCS. However, the sorption enhanced reforming and the entrained flow gasifiers are more suited to this scope than the heat pipe reformer, because higher overall CO2 capture rates can be achieved. As CO2 is from biogenic sources, the life cycle carbon footprint of the produced H2 is only slightly positive (without CCS) or negative (with CCS). This negative carbon footprint is not obtained at the cost of important trade-offs with regards to ecosystem quality, human health or resource depletion, with the exception of high forest land use. Fuel cell electric vehicles using hydrogen from biomass (both wood and biomethane) with CCS as fuel turn out to be the most climate friendly among all options, with even possible negative total greenhouse gas emissions. However, limited biomass resources and potential alternative uses need to be considered. This journal is ISSN:2398-4902

The size and shape characterization of platelike particles using a dual projection imaging device is presented. Based on the published algorithm to estimate the three lengths of the particles from the image pairs (method 1), the average error on the shortest length is around 140% on a test set of particles with different sizes, shapes, and alignment. Therefore, two potential improvements are tested in a simulation setting. The first approach uses an additional projection coupled with an oriented bounding box to estimate the three lengths (method 2). The second approach uses a machine learning model to estimate the three lengths from two projections (method 3). It is shown that method 2 marginally increases the accuracy, while method 3 leads to a significant improvement with an average error of 33% for the shortest characteristic length of particles in the test set and even less for the other lengths. It is shown that this remaining error is caused by the particle alignment with respect to the cameras. Since platelets cannot always be automatically distinguished from quasi-equant particles due to alignment issues, the model was also trained to estimate the three characteristic lengths of quasi-equant particles. The training set and the test set, used for model training and validation, respectively, comprise particles that exhibit quasi-equant, needlelike, and platelike shapes. Several machine learning models are identified and optimized to predict the three particle lengths based on the two projections from the imaging device. Artificial neural networks were chosen because of their superior predictive performance. © 2020 American Chemical Society, Industrial & Engineering Chemistry Research, 60 (1), ISSN:1520-5045, ISSN:0888-5885

This contribution introduces a novel carbon pricing system and illustrates its benefits. The system is based on two related but distinct ideas. First, we group the global pools of carbon into three aggregate pools, and we tax or credit human-caused carbon fluxes across the boundaries of the pools. Second, we base the tax or credit solely on physical movements of carbon between pools; hence, the system uses a physical baseline instead of a behavioral baseline based on the hypothetical emissions levels that would have arisen absent the carbon price. The proposed system goes beyond the limitations of current carbon pricing schemes for a number of reasons: it is designed to capture all positive and negative emissions based purely on their climate impact, allowing a broader scope and more appropriate incentives than current systems; it avoids creating bad incentives, particularly those caused by additionality requirements found in carbon offset systems; it captures the complexity of carbon movements through human and natural systems; it reduces measurement errors; and it provides transparent and easily observed price signals. Though this manuscript is conceptual in nature and refrains from discussing the technicalities related to the implementation of the proposed carbon pricing system, we trust that it may contribute to the development of policies enabling a net-zero and net-negative CO2-emissions world., Climatic Change, 171, ISSN:0165-0009, ISSN:1573-1480

Solid-state deracemization via temperature cycles is a technique that has been shown to be effective to isolate the pure enantiomer of a conglomerate-forming compound. This process has a large number of operating parameters that can be adjusted according to system-specific properties. On the one hand, this feature makes the process flexible and prone to optimization. On the other hand, the design space is so large that experimental optimization of the process can become long and cumbersome. In this work, we achieve two results. First, we show that deracemization via temperature cycles works very effectively for two new experimental systems, namely, the chiral compounds 2-(benzylideneamino)-2-(2-chlorophenyl)acetamide (CPG) and 3,3-dimethyl-2-((naphthalen-2-ylmethylene)amino)butanenitrile (tLEU). Second, we propose a new approach for the design of an effective deracemization process via temperature cycles for a new compound. Therefore, in this work, we investigate the effect of different operating conditions, namely, the initial enantiomeric excess, the cooling rate, the temperature range, and the catalyst concentration, on the performance of deracemization via temperature cycles for the new compounds CPG and tLEU and for N-(2-methylbenzylidene)phenylglycine amide (NMPA), which was already studied in a previous paper. On the basis of these outcomes, we conclude by proposing a model-free screening strategy for the design of an effective deracemization process via temperature cycles for a new compound., Organic Process Research & Development, 24 (8), ISSN:1083-6160, ISSN:1520-586X

In this paper, we assess the performance of vacuum pressure swing adsorption (VPSA) for co-purification of H2 and CO2 through modelling and process optimization. VPSA allows for the integration of ...

This study presents an integrated techno-environmental assessment of hydrogen production from natural gas and biomethane, combined with CO2 capture and storage (CCS). We have included steam methane reforming (SMR) and autothermal reforming (ATR) for syngas production. CO2 is captured from the syngas with a novel vacuum pressure swing adsorption (VPSA) process, that combines hydrogen purification and CO2 separation in one cycle. As comparison, we have included cases with conventional amine-based technology. We have extended standard attributional Life Cycle Assessment (LCA) following ISO standards with a detailed carbon balance of the biogas production process (via digestion) and its by-products. The results show that the life-cycle greenhouse gas (GHG) performance of the VPSA and amine-based CO2 capture technologies is very similar as a result of comparable energy consumption. The configuration with the highest plant-wide CO2 capture rate (almost 100% of produced CO2 captured) is autothermal reforming with a two-stage water-gas shift and VPSA CO2 capture – because the latter has an inherently high CO2 capture rate of 98% or more for the investigated syngas. Depending on the configuration, the addition of CCS to natural gas reforming-based hydrogen production reduces its life-cycle Global Warming Potential by 45–85 percent, while the other environmental life-cycle impacts slightly increase. This brings natural gas-based hydrogen on par with renewable electricity-based hydrogen regarding impacts on climate change. When biomethane is used instead of natural gas, our study shows potential for net negative greenhouse gas emissions, i.e. the net removal of CO2 over the life cycle of biowaste-based hydrogen production. In the special case where the biogas digestate is used as agricultural fertiliser, and where a substantial amount of the carbon in the digestate remains in the soil, the biowaste-based hydrogen reaches net-negative life cycle greenhouse gas emissions even without the application of CCS. Addition of CCS to biomethane-based hydrogen production leads to net-negative emissions in all investigated cases. ISSN:2398-4902

An overall techno-economic assessment of a post-combustion CO2 capture process using aqueous piperazine is presented. A two-step techno-economic optimization approach is developed and implemented. First, two-objective technical optimization problems are solved at different combinations of CO2 capture efficiencies and CO2 concentrations in the flue gas, which aim at minimizing the specific equivalent work while maximizing the volume-based productivity of the capture process. Increasing minimum specific reboiler duties between 2.4 and 2.9 MJthkgCO2captured−1 are obtained for decreasing flue gas CO2 concentrations between 33 and 4 vol%, on a dry basis, with absorber packing heights below 10 m. Then, costs are computed at the technical optimal conditions as a function of the CO2 capture efficiency, flue gas flowrate and CO2 concentration. As a result, maps of minimum cost of CO2 captured, of minimum cost of CO2 avoided, and of minimum cost of CO2 generated by the CO2 point source are obtained, as well as of the associated optimal operating conditions and performance indicators of the capture process, which allow to assess the economic feasibility and performance of the capture process under different cost scenarios and assumptions when applied to different flue gas compositions and flowrates typical of industrial CO2 intensive point sources., International Journal of Greenhouse Gas Control, 114, ISSN:1750-5836, ISSN:1878-0148

Secondary nucleation, in the absence of attrition, is known to be dependent on external fields, such as contact forces, shear, or interparticle forces. In this contribution, the thermodynamic effect of the presence of the seed crystal surface on secondary nucleation is derived in the context of the classical nucleation theory. The Gibbs free energy for the formation of a cluster close to a seed crystal is calculated with the addition of interparticle energies, namely, van der Waals attractive forces and Born repulsive forces. This results in the stabilization of a subcritical cluster close to the seed surface that can become a secondary nucleus more easily than under homogeneous nucleation conditions. Far from the seed surface, the developed model is reduced to the homogeneous nucleation described by the classical nucleation theory. The crystallization of paracetamol from an ethanol solution is taken as a case study, and the stabilization effect, given by the presence of interparticle energies, can be observed at different values of supersaturation. Three key indicators have been defined and calculated to describe the intensity of the stabilization effect, two of which, namely, the distance from the seed surface where the stabilization is active and the enhancement factor for supersaturation, are used in Part II of this series to describe the kinetics of secondary nucleation by interparticle energies., Crystal Growth & Design, 22 (1), ISSN:1528-7483, ISSN:1528-7505

Packed open-cell foams are proposed as an alternative to standard packed bed configuration commonly adopted for the adsorption columns of a temperature swing adsorption process. In this contribution, heat transfer in an adsorption column with a packed foam configuration is investigated by experimental and modeling analysis, in comparison to a standard packed bed. The introduction of the packed foam allows for more rapid temperature transitions and substantial reduction of temperature gradients within the adsorption bed. The impact of this heat transfer enhancement on the separation performance of a temperature swing adsorption process is evaluated by modeling an example post-combustion CO2 capture application. Although the presence of the foam implies a loss of sorbent inventory (-26.5%), higher process productivity (+80%) is achieved thanks to faster temperature swings and more homogeneous temperature distribution within the adsorption columns., Chemical Engineering Journal, 430 (3), ISSN:0300-9467, ISSN:1385-8947, ISSN:1873-3212, ISSN:0923-0467

Despite the growing evidence for the existence of amorphous mesoscopic species in a solution and their crucial roles in crystallization, there has been the lack of a suitable method to measure the time-resolved concentrations of amorphous and crystalline mesospecies in a lab-scale stirred reactor. This has limited experimental investigations to understand the kinetics of amorphous and crystalline mesospecies formation in stirred solutions and made it challenging to measure the crystal nucleation rate directly. Here, we used depolarized light sheet microscopy to achieve time-resolved measurements of amorphous and crystalline mesospecies concentrations in solutions at varying temperatures. After demonstrating that the concentration measurement method is reasonably accurate, precise, and sensitive, we utilized this method to examine mesospecies formation both in a mixture of two miscible liquids and in an undersaturated solution of DL-valine, thus revealing the importance of a temperature change in the formation of metastable and amorphous mesospecies as well as the reproducibility of the measurements. Moreover, we used the presented method to monitor both mesospecies formation and crystal nucleation in DL-valine solutions at four different levels of supersaturation, while achieving the direct measurement of the crystal nucleation rates in stirred solutions. Our results show that, as expected, the inherent variability in nucleation originating from its stochastic nature reduces with increasing supersaturation, and the dependence of the measured nucleation rate on supersaturation is in reasonable agreement with that predicted by the classical nucleation theory., Crystal Growth & Design, 22 (8), ISSN:1528-7483, ISSN:1528-7505

The effect of molecular cluster formation on the estimation of kinetic parameters for primary nucleation and growth in different systems has been studied using computationally generated data and three sets of experimental data in the literature. It is shown that the formation of molecular clusters decreases the concentration of monomers and hence the thermodynamic driving force for crystallization, which consequently affects the crystallization kinetics. For a system exhibiting a strong tendency to form molecular clusters, accounting for cluster formation in a kinetic model is critical to interpret kinetic data accurately, for instance, to estimate the specific surface energy γ from a set of primary nucleation rates. On the contrary, for a system with negligible cluster formation, a consideration of cluster formation does not affect parameter estimation outcomes. Moreover, it is demonstrated that using a growth kinetic model that accounts for cluster formation allows the estimation of γ from typical growth kinetic data (i.e., de-supersaturation profiles of seeded batch crystallization), which is a novel method of estimating γ developed in this work. The applicability of the novel method to different systems is proven by showing that the estimated values of γ are closely comparable to the actual values used for generating the kinetic data or the corresponding estimates reported in the literature., Crystal Growth & Design, 22 (1), ISSN:1528-7483, ISSN:1528-7505

This work presents a mathematical model that describes growth, homogeneous nucleation, and secondary nucleation that is caused by interparticle interactions between seed crystals and molecular clusters in suspension. The model is developed by incorporating the role of interparticle energies into a kinetic rate equation model, which yields the time evolution of nucleus and seed crystal populations, as in a population balance equation model, and additionally that of subcritical molecular clusters, thus revealing an important role of each population in crystallization. Seeded batch crystallization at a constant temperature has been simulated to demonstrate that the interparticle interactions increase the concentration of the critical clusters by several orders of magnitude, thus causing secondary nucleation. This explains how secondary nucleation can occur at a low supersaturation that is insufficient to trigger primary nucleation. Moreover, a sensitivity analysis has shown that the intensity of the interparticle energies has a major effect on secondary nucleation, while its effective distance has a minor effect. Finally, the simulation results are qualitatively compared with experimental observations in the literature, thus showing that the model can identify operating conditions at which primary or secondary nucleation is more prone to occur, which can be used as a useful tool for process design., Crystal Growth & Design, 22 (1), ISSN:1528-7483, ISSN:1528-7505

Bioenergy with carbon capture and storage (BECCS) is a carbon dioxide removal (CDR) solution necessary to achieve net-zero-carbon-emissions goals. While the BECCS potential from large industrial emitters has been quantified, the BECCS potential of small emitters, such as biogas facilities, has not been investigated. Moreover, most BECCS solutions rely on the expected availability of large geological storage capacity for future CDR implementation, although the deployment of CO2 transport and storage supply chains is still a barrier for geological carbon storage ambitions. An alternative opportunity for permanent sequestration of CO2 is concrete, in which captured CO2 can be permanently fixed through carbon dioxide mineralization technologies. We describe and discuss this solution by quantifying the potential of a European bioenergy with carbon capture, utilization, and storage (BECCUS) supply chain, which relies on biogenic CO2 from biogas facilities as a CO2 source, and on carbon dioxide mineralization in concrete as a permanent CO2 sink. This solution is available today, can be adopted seamlessly, and does not need economies of scale for its deployment. We find that European biogas facilities produce 24 Mtons of biogenic CO2 per year, of which 4 Mtons of CO2 per year are emitted from facilities already upgrading biogas into bio-methane. We estimate that carbon dioxide mineralization in recycled concrete aggregates in Europe could permanently store up to 8 Mtons of CO2 per year. Despite the limited storage potential, BECCUS supply chains would reduce CO2 transportation distance and system complexity compared to BECCS supply chains, and would result in a marketable product, namely concrete. Overall, carbon dioxide mineralization in recycled concrete aggregates combines carbon utilization with permanent sequestration, hence contributing to carbon-neutrality goals., Resources, Conservation and Recycling, 184, ISSN:0921-3449, ISSN:1879-0658

Solid-state deracemization via temperature cycles converts a racemic crystal mixture into an enantiopure product by periodic cycling of the temperature in the presence of a racemization catalyst. A continuous counterpart of this conventional batch-operated process is proposed that can be performed in mixed suspension mixed product removal crystallizers (MSMPRCs). More specifically, three different configurations are described to perform periodic forcing via temperature cycles, which differ from each other in the type of the feed and in the withdrawal system. We have developed a model by extending our recent population balance equation model of batch solid-state deracemization via temperature cycles, and we exploit this tool to analyze the start-up and periodic steady-state behavior. Moreover, we compare the performance of the different configurations based on the selected key performance indicators, namely, average periodic steady-state enantiomeric excess and productivity. The process with solution feed yields pure enantiomers, while the solid and suspension-fed process alternatives result in highly enantiomerically enriched crystals. We further design an MSMPRC cascade to overcome this purity limitation. This work discusses guidelines on how to transform the batch process of temperature cycles into a continuous operation, which enables stable, unattended operation and chiral crystal production with consistent product quality., Crystal Growth & Design, 22 (3), ISSN:1528-7483, ISSN:1528-7505

A nucleation rate model for describing the kinetics of secondary nucleation caused by interparticle energies (SNIPEs) is derived theoretically, verified numerically, and validated experimentally. The theoretical derivation reveals that the SNIPE mechanism can be viewed as enhanced primary nucleation, i.e., primary nucleation with a lower thermodynamic energy barrier (for nucleation) and a smaller critical nucleus size, both caused by the interparticle interactions and the associated energy between the surface of a seed crystal and a molecular cluster in solution, as shown in part I of this series. In the case of a sufficiently agitated suspension, the model depends on four parameters: two reflecting primary nucleation kinetics and the other two accounting for the intensity and effective spatial range of the interparticle interactions. As a numerical verification of the model, we show that the nucleation kinetics described by the SNIPE rate model is in quantitative agreement with those given by the kinetic rate equation model developed in part II of this series. A sensitivity analysis of the SNIPE rate model is conducted to present the effect of key model parameters on the nucleation kinetics. Moreover, the SNIPE rate model is validated by fitting the model to the time-resolved data of secondary nucleation experiments as well as to two other, well-known secondary nucleation rate models. Importantly, all of the estimated parameter values for the SNIPE model were consistent with the theoretical estimates, while some of the estimated parameter values for one of the well-known secondary nucleation models deviated from the corresponding theoretical values significantly., Crystal Growth & Design, 22 (6), ISSN:1528-7483, ISSN:1528-7505

In this work, we use surrogate models to accelerate the optimization of an adsorption process for H2 purification and CO2 capture within the context of fossil-based low-carbon H2 production. A one dimensional column model was used to generate a training set for different feed compositions with up to four impurities and for varying process conditions. Subsequently, an artificial neural network (ANN) surrogate model was trained for six key performance indicators, achieving adjusted R2 values over 0.999 for all indicators. Finally, the ANN was used for the constrained optimization of the H2 separation performance and of the process performance (energy consumption and productivity), and the results were compared to full model optimization results. The agreement is very good for the H2 separation performance, and in the case of low H2 purity targets (99%) also for the process performance. For higher H2 purities, however, the energy-productivity Pareto front features a very high sensitivity toward the H2 purity constraint, and even small deviations in H2 purity between full model and ANN surrogate model can translate to big deviations in the energy-productivity Pareto front. This is particularly pronounced for poorly sampled input regions at the edge of the sampling domain, for example for a binary H2-CO2 feed. If the ANN surrogate model is used at such edges of the sampling domain, additional sampling is required in this region to increase its accuracy. For all other cases, the deviations between the full model and the ANN surrogate model regarding the minimum energy consumption (or the maximum productivity) were well below 5%, showing that the ANN can be used with good accuracy instead of the full model., Computers and Chemical Engineering, 166