A shrinking core model for steam hydration of CaO-based sorbents cycled for CO2 capture

Calcium looping is a developing CO2 capture technology. It is based on the reversible carbonation of CaO sorbent, which becomes less reactive upon cycling. One method of increasing the reactivity of unreactive sorbent is by hydration in the calcined (CaO) form. Here, sorbent has been subjected to repeated cycles of carbonation and calcination within a small fluidised bed reactor. Cycle numbers of 0 (i.e., one calcination), 2, 6 and 13 have been studied to generate sorbents that have been deactivated to different extents. Subsequently, the sorbent generated was subjected to steam hydration tests within a thermogravimetric analyser, using hydration temperatures of 473, 573 and 673 K. Sorbents that had been cycled less prior to hydration hydrated rapidly. However, the more cycled sorbents exhibited behaviour where the hydration conversion tended towards an asymptotic value, which is likely to be associated with pore blockage. This asymptotic value tended to be lower at higher hydration temperatures; however, the maximum rate of hydration was found to increase with increasing hydration temperature. A shrinking core model has been developed and applied to the data. It fits data from experiments that did not exhibit extensive pore blockage well, but fits data from experiments that exhibited pore blockage less well

An overview of advances in biomass gasification

Biomass gasification is a widely used thermochemical process for obtaining products with more value and potential applications than the raw material itself. Cutting-edge, innovative and economical gasification techniques with high efficiencies are a prerequisite for the development of this technology. This paper delivers an assessment on the fundamentals such as feedstock types, the impact of different operating parameters, tar formation and cracking, and modelling approaches for biomass gasification. Furthermore, the authors comparatively discuss various conventional mechanisms for gasification as well as recent advances in biomass gasification. Unique gasifiers along with multi-generation strategies are discussed as a means to promote this technology into alternative applications, which require higher flexibility and greater efficiency. A strategy to improve the feasibility and sustainability of biomass gasification is via technological advancement and the minimization of socio-environmental effects. This paper sheds light on diverse areas of biomass gasification as a potentially sustainable and environmentally friendly technology

Progress in biofuel production from gasification

Biofuels from biomass gasification are reviewed here, and demonstrated to be an attractive option. Recent progress in gasification techniques and key generation pathways for biofuels production, process design and integration and socio-environmental impacts of biofuel generation are discussed, with the goal of investigating gasification-to-biofuels’ credentials as a sustainable and eco-friendly technology. The synthesis of important biofuels such as bio-methanol, bio-ethanol and higher alcohols, bio-dimethyl ether, Fischer Tropsch fuels, bio-methane, bio-hydrogen and algae-based fuels is reviewed, together with recent technologies, catalysts and reactors. Significant thermodynamic studies for each biofuel are also examined. Syngas cleaning is demonstrated to be a critical issue for biofuel production, and innovative pathways such as those employed by Choren Industrietechnik, Germany, and BioMCN, the Netherlands, are shown to allow efficient methanol generation. The conversion of syngas to FT transportation fuels such as gasoline and diesel over Co or Fe catalysts is reviewed and demonstrated to be a promising option for the future of biofuels. Bio-methane has emerged as a lucrative alternative for conventional transportation fuel with all the advantages of natural gas including a dense distribution, trade and supply network. Routes to produce H2 are discussed, though critical issues such as storage, expensive production routes with low efficiencies remain. Algae-based fuels are in the research and development stage, but are shown to have immense potential to become commercially important because of their capability to fix large amounts of CO2, to rapidly grow in many environments and versatile end uses. However, suitable process configurations resulting in optimal plant designs are crucial, so detailed process integration is a powerful tool to optimize current and develop new processes. LCA and ethical issues are also discussed in brief. It is clear that the use of food crops, as opposed to food wastes represents an area fraught with challenges, which must be resolved on a case by case basis

Gene Expression Meta-Analysis Identifies VDAC1 as a Predictor of Poor Outcome in Early Stage Non-Small Cell Lung Cancer

The bioenergetic status of non-small cell lung cancer correlates with tumour aggressiveness. The voltage dependent anion channel type 1 (VDAC1) is a component of the mitochondrial permeability transition pore, regulates mitochondrial ATP/ADP exchange suggesting that its over-expression could be associated with energy dependent processes including increased proliferation and invasiveness. To test this hypothesis, we conducted an in vivo gene-expression meta-analysis of surgically resected non-small cell lung cancer (NSCLC) using 602 individual expression profiles, to examine the impact of VDAC1 on survival.High VDAC1 expression was associated with shorter overall survival with hazard ratio (HR) = 0.6639 (95% confidence interval (CI) 0.4528 to 0.9721), p = 0.035352 corresponding to 52 versus 101 months. VDAC1 predicted shorter time to recurrence and was shown to be an independent prognostic factor compared with histology, gender, age, nodal stage and tumour stage in a Cox multivariate analysis. Supervised analysis of all the datasets identified a 6-gene signature comprising HNRNPC, HSPA4, HSPA9, UBE2D2, CSNK1A1 and G3BP1 with overlapping functions involving regulation of protein turnover, RAS-RAF-MEK pathway and transcription. VDAC1 predicted survival in breast cancer and myeloma and an unsupervised analysis revealed enrichment of the VDAC1 signature in specific subsets.In summary, gene expression analysis identifies VDAC1 gene expression as a predictor of poor outcome in NSCLC and other cancers and is associated with dysregulation of a conserved set of biological pathways, which may be causally associated with aggressive tumour behaviour

Pilot testing of enhanced sorbents for calcium looping with cement production

One of the main challenges for commercialising calcium looping (CaL) as a CO2 capture technology is maintaining a high level of sorbent reactivity during long-term cycling. In order to mitigate the decay in carrying capacity, research has moved towards producing enhanced sorbents. However, this creates potential problems related to ease of scaling up production techniques and production costs, and raises the question as to whether such approaches can be used at large scale. On the other hand, a key advantage of CaL over other carbon capture technologies is synergy with the cement industry, i.e., use of spent sorbent as a feedstock for clinker production. In this work two enhanced materials: (i) limestone doped with HBr through a particle surface impregnation technique; and (ii) pellets prepared from limestone and calcium aluminate cement, were tested in a 25 kWth dual fluidised bed pilot-scale reactor in order to investigate their capture performance and mechanical stability under realistic CaL conditions. Moreover, the spent sorbent was then used as a raw material to make cement, which was characterised for phase and chemical composition as well as compressive strength. The HBr-doped limestone showed better performance in terms of both mechanical strength and stability of the CO2 uptake when compared to that of pellets. Furthermore, it was shown that the cement produced has similar characteristics and performance as those of commercial CEM 1 cement. This indicates the advantages of using the spent sorbent as feedstock for cement manufacture and shows the benefits of synthetic sorbents in CaL and suitability of end-use of spent sorbents for the cement industry, validating their synergy at pilot scale. Finally, this study demonstrates the possibility of using several practical techniques to improve the performance of CaL at the pilot scale, and more importantly demonstrates that commercial-grade cement can be made from the lime product from this technology

Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: characterizations and DFT analysis

Is it possible to improve CO2 solubility in potassium carbonate (K2CO3)-based transition temperature mixtures (TTMs)? To assess this possibility, a ternary transition-temperature mixture (TTTM) was prepared by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform infrared spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliphatic functional groups in the prepared solvents. From thermogravimetric analysis (TGA), it was found that the addition of AMPD to the binary mixture can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temperature. In addition, Eyring’s absolute rate theory was used to compute the activation parameters (∆G*, ∆H*, and ∆S*). The CO2 solubility in liquids was measured at a temperature of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO2 solubility of TTTM was improved by the addition of AMPD. At the pressure of about 1.8 MPa, the CO2 mole fractions of TTM and TTTM were 0.1697 and 0.2022, respectively. To confirm the experimental data, density functional theory (DFT) was employed. From the DFT analysis, it was found that the TTTM + CO2 system has higher interaction energy (|∆E|) than the TTM + CO2 system indicating the higher CO2 affinity of the former system. This study might help scientists to better understand and to improve CO2 solubility in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD

Lime-Based Sorbents for High-Temperature CO2 Capture—A Review of Sorbent Modification Methods

This paper presents a review of the research on CO2 capture by lime-based looping cycles undertaken at CanmetENERGY’s (Ottawa, Canada) research laboratories. This is a new and very promising technology that may help in mitigation of global warming and climate change caused primarily by the use of fossil fuels. The intensity of the anticipated changes urgently requires solutions such as more cost-effective technologies for CO2 capture. This new technology is based on the use of lime-based sorbents in a dual fluidized bed combustion (FBC) reactor which contains a carbonator—a unit for CO2 capture, and a calciner—a unit for CaO regeneration. However, even though natural materials are cheap and abundant and very good candidates as solid CO2 carriers, their performance in a practical system still shows significant limitations. These limitations include rapid loss of activity during the capture cycles, which is a result of sintering, attrition, and consequent elutriation from FBC reactors. Therefore, research on sorbent performance is critical and this paper reviews some of the promising ways to overcome these shortcomings. It is shown that reactivation by steam/water, thermal pre-treatment, and doping simultaneously with sorbent reforming and pelletization are promising potential solutions to reduce the loss of activity of these sorbents over multiple cycles of use

Safety and pharmacokinetics of multiple dose myo-inositol in preterm infants

BACKGROUND: Preterm infants with respiratory distress syndrome (RDS) given inositol had reduced bronchopulmonary dysplasia (BPD), death and severe retinopathy of prematurity (ROP). We assessed the safety and pharmacokinetics of daily inositol to select a dose providing serum levels previously associated with benefit, and to learn if accumulation occurred when administered throughout the normal period of retinal vascularization. METHODS: Infants ≤ 29 wk GA (n = 122, 14 centers) were randomized and treated with placebo or inositol at 10, 40, or 80 mg/kg/d. Intravenous administration converted to enteral when feedings were established, and continued to the first of 10 wk, 34 wk postmenstrual age (PMA) or discharge. Serum collection employed a sparse sampling population pharmacokinetics design. Inositol urine losses and feeding intakes were measured. Safety was prospectively monitored. RESULTS: At 80 mg/kg/d mean serum levels reached 140 mg/l, similar to Hallman's findings. Levels declined after 2 wk, converging in all groups by 6 wk. Analyses showed a mean volume of distribution 0.657 l/kg, clearance 0.058 l/kg/h, and half-life 7.90 h. Adverse events and comorbidities were fewer in the inositol groups, but not significantly so. CONCLUSION: Multiple dose inositol at 80 mg/kg/d was not associated with increased adverse events, achieves previously effective serum levels, and is appropriate for investigation in a phase III trial