Michael Specht

High temperature absorbents for CO 2 capture

Publisher Summary The development of suitable low-cost, regenerable absorbents with long lifetime is one of the major challenges of the high temperature CO2 capture. The purpose of the experiment described in this chapter is to carry out a screening of natural minerals that are able to take up CO2 in a reversible manner. The selected minerals were characterized in terms of absorption capacity, cycle stability, and mechanical stability. Furthermore, the influence of different parameters such as presence of steam, particle size, and sorbent loading degree on the cycle stability was investigated. The tested minerals were selected among different classes of carbonates and silicates. Thermogravimetric analysis was performed employing a Netzsch apparatus STA 409 CD. Experiments were conducted in isothermal and quasi-isothermal manner. The quasi-isothermal experiments were carried out in controlled gas flow atmosphere. The chemical/cycling stability is dependent on the chemical composition of the minerals; an increased concentration of inert components influences positively the cycling stability of the sorbent materials. Natural complex silicates containing calcium carbonate showed poor CO2 sorbent qualities, however, they produced good cycling and mechanical stability results. The presence of steam in the gas atmosphere increases the absorption reaction rate, but reduces the sorbent lifetime. Crushing and milling can influence the absorption behavior of the sorbents due to the change of their chemical composition.

Natural Gas and Renewable Methane

According to current thinking, natural gas is a fossil energy carrier that, just like oil, underwent organic transformation under high pressure and in the absence of oxygen in the interior of the earth and therefore its composition as a naturally occurring product varies according to its geological source. The main component is always methane, which varies between 75 and 98 %. Other components include nitrogen, ethane and carbon dioxide.

Erdgas und erneuerbares Methan

Nach gangiger Hypothese ist Erdgas ein fossiler Energietrager, der wie Erdol durch Umwandlungsprozesse organischer Stoffe unter hohem Druck und unter Abwesenheit von Sauerstoff im Erdinneren entstand und daher als Naturprodukt abhangig vom geologischen Fundort in seiner Zusammensetzung schwankt. Der Hauptanteil ist immer Methan, der zwischen 75 bis 98 % variiert. Die weiteren Anteile bestehen hauptsachlich aus Stickstoff, Ethan und Kohlenstoffdioxid. Bei der Erdgasaufbereitung wird das gewonnene Erdgas zunachst von Schwefel und anderen storenden Komponenten gereinigt, und es werden durch Trocknungsprozesse Wasser und langkettige Kohlenwasserstoffe dem Gas entzogen. Die Rolle des Erdgases beim Ausbau alternativer und erneuerbarer Energien ist von wachsender Bedeutung. Derzeit werden in Deutschland circa 80 % des Erdgases im Warmemarkt verwendet, das heist Erdgas wird nur zum geringeren Teil in der Stromerzeugung oder im Bereich der Mobilitat eingesetzt [1]. Jedoch wird im Verkehrssektor der Einsatz stetig zunehmen.