Influence of low-temperature electrolyser design on economic and environmental potential of CO and HCOOH production: A techno-economic assessment

The electrochemical conversion of excess CO2 into valuable chemicals, such as carbon monoxide (CO) and formic acid (HCOOH) offers the possibility of combating climate change, while simultaneously providing sustainable raw materials for the chemical industry. The system design choice has large implications for the economic competitiveness of such processes. The impact of low-temperature electrolyser design on the economic potential of CO and HCOOH production was investigated alongside an environmental assessment of the required chemical plants. Six different cell architectures were analysed in a base and an optimistic case scenario with a target production of 75 and 100 tProduct/day, respectively, and a projected plant lifetime of 25 years. While none of the CO architectures managed to operate profitably in the base case, the modelling of both HCOOH architectures yielded a positive economic outcome. The CO producing systems showed an on average 22% greater performance improvement in the optimistic case, compared to HCOOH. The environmental potential to act as a carbon sink was determined through an analysis of the CO2 emissions due to heat and electricity demand as well as the CO2 utilisation of the systems. While HCOOH production requires clean electricity with maximum carbon intensities of 137 gCO2/kWh in the optimistic case, CO production only requires a maximum of 346 gCO2/kWh, which is well above the current EU electricity mix of 235 gCO2/kWh.ISSN:1364-032

Experimental Study of Local Axial Mixing in a Pilot-Scale Cold Burner

The residence time distribution (RTD) approach was used to characterize the flow and mixing behavior of burners. This analysis consists of injecting an inert gaseous tracer into the feed and measuring its change in concentration at various detection points. The responses are then used to characterize the flow behavior and, thus, the local mixing in the space delimited by the injection and probe points. The outcome of this RTD analysis is a flow model that, combined with an appropriate kinetics, constitutes an efficient tool in examining the ways to reduce NOx emissions in existing installations. A replica made in plastic at a 1:1 scale of an industrial gas burner was used for cold experiments. As preliminary information, a chart of local mixing in the axial section of the burner chamber was obtained. Even though far from working conditions, cold experiments are beneficial because they reveal the existence of possible major flow disturbances, leading to imperfect or incomplete combustion, a source of NOx

Optimization of Chitosan Extraction Process from <i>Rapana venosa</i> Egg Capsules Waste Using Experimental Design

New green and sustainable sources were chosen to obtain chitosan, an important material, with many applications in different fields. The present study is focused on egg capsules of Rapana venosa waste as raw material for chitosan oligomers. As previous studies revealed that chitosan extraction from this material takes place with a low yield, the present research aimed to optimize this step. A 22 experimental plan, with three replicates in the center, was proposed to investigate the influence of NaOH concentration and temperature on the yield extraction. After a primary analysis of the experimental data, a favorable temperature value was selected (90 °C) at which the total dissolution of the egg capsules was obtained. Then, at this temperature, the experimental plan was extended exploring the influence of the NaOH concentration on three levels (5, 6, and 7%) and the extraction duration on two levels (60 and 85 min). Based on all experimental data, a neural model was obtained and validated. The neural model was used to maximize the yield, applying Genetic Algorithm (GA) implemented in Matlab®. The resulting optimal solution is: NaOH concentration 6.47%, temperature 90 °C, duration 120 min, with a yield value of 7.05%

Crabs Marine Waste—A Valuable Source of Chitosan: Tuning Chitosan Properties by Chitin Extraction Optimization

Chitin extraction from crab shells was studied experimentally and optimized aiming to obtain chitosan with predefined deacetylation degree and molecular mass. To find out the optimum operating conditions that ensure the obtaining of a chitosan with highest deacetylation degree and specific molecular mass four parameters were varied: the concentration of NaOH and the temperature for deproteinization step, respectively HCl concentration and the number of acidic treatments for the demineralization stage. The experiment was carried on following Taguchi orthogonal array L9, and the best combination of factors was found using the desirability function approach. The optimization results showed that 5% NaOH concentration and low temperatures lead to a chitosan with high deacetylation degree. High molecular mass chitosan is obtained when a single step acidic treatment is used, while a chitosan with low molar mass is obtained for multiple acid contacts and higher HCl concentration