Experimental Modeling of Ankerite–Pyrite Interaction under Lithospheric Mantle P–T Parameters: Implications for Graphite Formation as a Result of Ankerite Sulfidation

Experimental modeling of ankerite–pyrite interaction was carried out on a multi-anvil high-pressure apparatus of a “split sphere” type (6.3 GPa, 1050–1550 °C, 20–60 h). At T ≤ 1250 °C, the formation of pyrrhotite, dolomite, magnesite, and metastable graphite was established. At higher temperatures, the generation of two immiscible melts (carbonate and sulfide ones), as well as graphite crystallization and diamond growth on seeds, occurred. It was established that the decrease in iron concentration in ankerite occurs by extraction of iron by sulfide and leads to the formation of pyrrhotite or sulfide melt, with corresponding ankerite breakdown into dolomite and magnesite. Further redox interaction of Ca,Mg,Fe carbonates with pyrrhotite (or between carbonate and sulfide melts) results in the carbonate reduction to C0 and metastable graphite formation (±diamond growth on seeds). It was established that the ankerite–pyrite interaction, which can occur in a downgoing slab, involves ankerite sulfidation that triggers further graphite-forming redox reactions and can be one of the scenarios of the elemental carbon formation under subduction settings.

INVESTIGATION OF THE PROCESSES OF THERMAL DESTRUCTION OF CELLULOSE-CONTAINING (PAPER) WASTE

Materials of practical research work on thermal destruction of paper waste were presented. The main task was The comprehensive study of the aspects of carbon formation on the basis of analytical studies was considered, as well as using a specially built laboratory installation — a waste graphitizer. Research has been carried out on the effectivity of application of pyrolysis gases of the process as fuel to maintain the temperatures of the thermal destruction reaction. Practical examples have proved the possibility and expediency of using the solid residue of the reaction as a component in various fields of production. Bibl. 10, Fig. 1, Tab. 3.

Combination of b-Fuels and e-Fuels—A Technological Feasibility Study

The energy supply in Austria is significantly based on fossil natural gas. Due to the necessary decarbonization of the heat and energy sector, a switch to a green substitute is necessary to limit CO2 emissions. Especially innovative concepts such as power-to-gas establish the connection between the storage of volatile renewable energy and its conversion into green gases. In this paper, different methanation strategies are applied on syngas from biomass gasification. The investigated syngas compositions range from traditional steam gasification, sorption-enhanced reforming to the innovative CO2 gasification. As the producer gases show different compositions regarding the H2/COx ratio, three possible methanation strategies (direct, sub-stoichiometric and over-stoichiometric methanation) are defined and assessed with technological evaluation tools for possible future large-scale set-ups consisting of a gasification, an electrolysis and a methanation unit. Due to its relative high share of hydrogen and the high technical maturity of this gasification mode, syngas from steam gasification represents the most promising gas composition for downstream methanation. Sub-stoichiometric operation of this syngas with limited H2 dosage represents an attractive methanation strategy since the hydrogen utilization is optimized. The overall efficiency of the sub-stoichiometric methanation lies at 59.9%. Determined by laboratory methanation experiments, a share of nearly 17 mol.% of CO2 needs to be separated to make injection into the natural gas grid possible. A technical feasible alternative, avoiding possible carbon formation in the methanation reactor, is the direct methanation of sorption-enhanced reforming syngas, with an overall process efficiency in large-scale applications of 55.9%.