Gas adsorptive properties of manganese dioxides

二氧化锰的气体吸附性能

• 批准号: 03640662
• 负责人: MIURA Hiroyuki
• 金额: $ 1.28万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03640662/
• 关键词: manganese dioxide; gas adsorption; carbon dioxide; manganese dioxide mineral; ramsdellite; groutite; 炭酸マンガン; 二酸化マンガン国際標準サンプル

Manganese oxide minerals adsorb some kinds of gas molecules on their surface and released them on heating. The released gas from natural and synthetic manganese oxide minerals was studied by Q-pole mass spectrometer. CO_2 was observed in the temperature range 100-350 ﾟC, 400-450ﾟC and 600-700ﾟC. The released CO_2 gas between 100 and 350 ﾟC derived from the surface adsorption. Natural and synthetic manganese dioxide minerals adsorb CO_2 gas in the air readily.Manganese hydroxide mineral was synthesized by the reduction of ramsdellite (gamma-MnO_2) using hydrothermal techniques in order to find the new manganese oxide which adsorb CO_2 gas. Powdered ramsdellite and manganese metal was sealed in a Pt tube with water and keep it at 150 ﾟC, 1000 kb for 10 days. The reaction is written as follows. 8MnO_2 + 2H_2O + Mn -> 4Mn_2O_3(OH) + MnO_2. Manganese metal is added to reduce the oxygen pressure in the tube and stabilize manganese ion as Mn^<3+> and Mn^<4+>. The X-ray powder diffraction profile of the product is quite similar to that of ramsdellite and groutite( gamma-MnOOH). The crystal structure, refined by the Retveldt method, is isostructure to ramsdellite and groutite. The ideal formula for the product is Mn^<3+>_2Mn^<4+>_2O_6(OH)_2. In the process of reduction, ramsdellite + new phase or new phase + groutite is observed. Therefore it is obvious that the solid solution between ramsdellite and groutite is absent.

氧化锰矿物在其表面吸附某些气体分子，加热后释放出来。采用Q-pole质谱仪对天然和合成氧化锰矿物的释放气体进行了研究。CO_2在100 ~ 350、400 ~ 450、600 ~ 700三个温度范围内均可观察到。表面吸附产生的CO_2在100 ~ 350℃之间。天然和合成二氧化锰矿物极易吸附空气中的CO_2气体。采用水热法还原ramsdellite （γ - mno_2）合成氢氧化锰矿物，以寻找吸附CO_2气体的新型氧化锰。将ramsdellite粉末和金属锰在Pt管中加水密封，在150 C， 1000 kb下保存10天。反应写如下。8MnO_2 + 2H_2O + Mn -> 4Mn_2O_3(OH) + MnO_2加入金属锰降低管内氧压，使锰离子稳定为Mn^<3+>和Mn^<4+>。该产物的x射线粉末衍射谱与拉姆斯特尔石和石英石（γ - mnooh）非常相似。经Retveldt法细化后，其晶体结构为ramsdellite和grouite的等晶结构。该产物的理想配方为Mn^<3+>_2Mn^<4+>_2O_6(OH)_2。在还原过程中，观察到拉姆斯特尔石+新相或新相+ grouite。因此，很明显，不存在拉姆斯特尔石与grouite之间的固溶体。