Search results for "hiilidioksidi"

Influence of a Cu–zirconia interface structure on CO2 adsorption and activation

2021

CO2 adsorption and activation on a catalyst are key elementary steps for CO2 conversion to various valuable products. In the present computational study, we screened different Cu–ZrO2 interface structures and analyzed the influence of the interface structure on CO2 binding strength using density functional theory calculations. Our results demonstrate that a Cu nanorod favors one position on both tetragonal and monoclinic ZrO2 surfaces, where the bottom Cu atoms are placed close to the lattice oxygens. In agreement with previous calculations, we find that CO2 prefers a bent bidentate configuration at the Cu–ZrO2 interface and the molecule is clearly activated being negatively charged. Strain…

Exploring CO2 hydrogenation to methanol at a CuZn–ZrO2 interface via DFT calculations

2023

Multi-component heterogeneous catalysts are among the top candidates for converting greenhouse gases into valuable compounds. Combinations of Cu, Zn, and ZrO2 (CZZ) have emerged as promisingly efficient catalysts for CO2 hydrogenation to methanol. To explore the catalytic mechanism, density functional theory (DFT) calculations and the energetic span model (ESM) were used to study CO2 conversion routes to methanol on CuZn–ZrO2 interfaces with a varying Zn content. Our results demonstrate that the presence of Zn sites at the interface improves CO2 binding. However, the adsorption and activation energies are insensitive to Zn concentration. The calculations also show that the hydrogenation of …

Uusiutuvat energiat : hiilidioksidin hyödyntäminen ja kuivamädätys

2012

Tämän julkaisun ensimmäisessä osassa selvitetään erilaisia mahdollisuuksia hyödyntää bio- ja puukaasun ohella muodostuvaa hiilidioksidia ja erityisesti sen hyötykäyttöä kasvihuoneympäristössä. Toisessa osassa käsitellään kuivamädätysteknologiaa sekä siihen liittyviä käyttökokemuksia kirjallisuuteen ja henkilökohtaisiin haastatteluihin pohjautuen. Julkaisun tarkoituksena on tukea uusiutuvaan energiaan liittyvää tutkimus- ja kehittämistoimintaa.

The influence of lipid content and taxonomic affiliation on methane and carbon dioxide production from phytoplankton biomass in lake sediment

2021

The greenhouse gases methane (CH4) and carbon dioxide (CO2) are end products of microbial anaerobic degradation of organic matter (OM) in lake sediments. Although previous research has shown that phytoplankton lipid content influences sediment methanogenesis, current understanding on how OM quality affects methanogenesis is still limited. Such information is needed to more accurately assess how lake greenhouse gas emissions may change in response to anthropogenic activities. We cultured 11 phytoplankton species from five classes and studied how taxonomic identity, C : N ratio, lipid content, and fatty acid composition of phytoplankton biomass affects the CH4 and net CO2 production in anaero…

Computational studies of chemical looping combustion materials and CO₂ activating surfaces

2016

Supplementing air with CO2 stripped from recirculating aquaculture improves growth of two green microalgae in aquaculture wastewater

2023

To improve sustainability and to implement the principles of circular economy in aquaculture, we tested the possibility to boost the capture of nitrate by two green microalgal species from recirculating aquaculture system's (RAS) wastewater by supplementing air with carbon dioxide stripped from a RAS. Carbon dioxide addition increased cell densities of Monoraphidium griffithii and Haematococcus pluvialis in photobioreactors during 9-day growing periods. However, growth rates and nitrate uptake rates were only improved for M. griffithii. Addition of CO2 decreased pH of the medium with M. griffithii which likely also affected positively on algal growth and nutrient uptake. These laboratory sc…

A Computational Study of Adsorption of CO2, SO2, and H2CO on Free-Standing and Molybdenum-Supported CaO Films

2019

Oxide films play a significant role in a wide range of fields from catalysis to solar cell materials. CaO films are promising sorbents for many environmentally harmful molecules. Here, we report a systematic investigation of adsorption of CO2, SO2, and H2CO on bulk and Mo-supported CaO(100) films using density functional theory. Significant effects on adsorption energy, charge transfer to the molecules, and degree of the C−O bond activation were demonstrated on Mo-supported CaO films by changing the film thickness, composition, and the strength and direction of an applied external electric field. These findings are relevant for interpreting results from scanning tunneling microscopy of smal…

Side‐on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel

2021

Abstract A nickel complex incorporating an N2O ligand with a rare η2‐N,N′‐coordination mode was isolated and characterized by X‐ray crystallography, as well as by IR and solid‐state NMR spectroscopy augmented by 15N‐labeling experiments. The isoelectronic nickel CO2 complex reported for comparison features a very similar solid‐state structure. Computational studies revealed that η2‐N2O binds to nickel slightly stronger than η2‐CO2 in this case, and comparably to or slightly stronger than η2‐CO2 to transition metals in general. Comparable transition‐state energies for the formation of isomeric η2‐N,N′‐ and η2‐N,O‐complexes, and a negligible activation barrier for the decomposition of the lat…

Responsibilities for just transition to low-carbon societies : a role-based framework

2022

Low-carbon transitions in industrialised societies will have significant social, economic and environmental impacts, raising concerns of justice. Calls for urgent transitions evoke a question about the roles of different actors in advancing transitions and ensuring they are just. While the responsibilities for emission mitigation have been long discussed, responsibilities for making a just transition have not. The question about responsibilities is particularly pressing because of the diverse constellation of actors involved in climate action, including diverse forms of non-state actors from city-level and business alliances to grassroots activists. We examine the responsibilities of state …

Mathematical modelling of sustainable bioresidual concrete

2019

In the production of cement, which is the main component of concrete production, the process generates about 5% of the global carbon dioxide emissions. In addition, bioproduct and pulp mills produce signi_cant quantities of soda ash and bio-ash, which is still largely unused. In this paper we will introduce our study related to improving the environmental friendliness of concrete used in construction by utilizing pulp mill waste while its long-term durability and strength and porosity properties meet the goals set for construction. The project `sustainable bioresidual concrete' is on-going and only preliminary numerical results with measurements are presented here. peerReviewed