Development of Selective Conversion Process of Fuel Nitrogen to N_2 with Metal Nanoparticles

金属纳米粒子选择性将燃料氮转化为N_2工艺的研究进展

• 批准号: 07555246
• 负责人: OHTSUKA Yasuo
• 金额: $ 5.63万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555246/
• 关键词: Fine metal particles; Coal; Fuel nitrogen; Inherent minerals; Nitrogen removal catalyst; Pyrolysis; Non-pollution; 脱窒素; 無公害化

1.Nanoscale FeOOH particles, precipitated onto low rank coals from an aqueous solution of FeCl_3 by using Ca(OH)_2, are reduced into metallic iron with the size of 20-30nm during fluidized bed pyrolysis, and metal nanoparticles promote efficient conversion of fuel nitrogen to N_2. There are two formation routes of N_2, secondary decomposition reactions of volatile nitrogen (tar, HCN,and NH_3) and conversion reactions of char nitrogen, and the latter is the main route with more highly-dispersed iron.2.When 15 coals with different ranks are pyrolyzed at 1000ﾟC with a fixed bed reactor, some low rank coals show extremely high conversion of fuel nitrogen to N_2,50-60%. Demineralization of these coals with HCl washing, XRD analyzes of low and high temperature ashes, and ICP analysis of HCl leachate lead to the conclusion that the presence of Fe-containing minerals in ion-exchangeable forms is the key factor determining for remarkable N_2 formation.3.The XPS and TEM-EDX measurements of the cahrs after pyrolysis reveal that such minerals are transformed into iron metal particles with the size of <approximately equal> 10nm, and that the mineral-derived iron show much higher activity for selective conversion of char nitrogen to N_2 than the externally-added iron. It is likely that iron-catalyzed solid phase reactions proceed through formation of interstitial iron nitrides and subsequent decomposition into N_2.4.Pyrolysis of these low rank coals with a free-fall type reactor is also carried out from a practical point of view, and it is suggested that tarry materials with pyrrolic and pyridinic nitrogen forms are converted to N_2 on the surface of the mineral-derived fine iron. When these compounds are passed over iron metal particles with the size of 20nm supported on pure carbon to verify this possibility, the conversion to N_2 take place exclusively.

1.用Ca（OH）_2从FeCl_3水溶液中沉淀到低阶煤上的纳米FeOOH颗粒，在流化床热解过程中被还原成20- 30 nm的金属铁，金属纳米颗粒促进燃料氮高效转化为N_2。N_2的生成途径有挥发分氮（焦油、HCN和NH_3）的二次分解反应和煤焦氮的转化反应两种，其中后者是主要的生成途径，铁的分散度较高。2.在固定床反应器中，对15种不同煤阶的煤在1000 ℃热解时，一些低阶煤的燃料氮转化率很高，达到50 - 60%。通过对这些煤的酸洗脱矿、高温灰和低温灰的XRD分析以及HCl浸出液的ICP分析，得出结论：铁矿物的存在是导致N_2生成的关键因素。3.热解后焦炭的XPS和TEM-EDX测试表明，铁矿物转化为粒径约为10 nm的铁金属颗粒<approximately equal>，且矿物铁的选择性转化N_2的活性远高于外加铁。铁催化的固相反应可能是通过形成间隙铁氮化物和随后分解成N_2来进行的。4.从实用的角度出发，还进行了这些低阶煤在自由落体式反应器中的热解，提出了具有吡咯和吡啶氮形式的焦油状物质在矿物衍生的细铁表面上转化为N_2的观点。当这些化合物通过负载在纯碳上的粒径为20 nm的铁金属颗粒时，证实了这种可能性，它们只发生向N_2的转化。

项目成果

Yasuo Ohtsuka: "Catalysis of fuel-nitrogen conversion to molecular nitrogen by iron" Third European Congress on Catalysis. (発表予定). (1997)

Yasuo Ohtsuka：“铁将燃料氮转化为分子氮的催化作用”，第三届欧洲催化大会（即将提交）。

Zhiheng Wu: "Nitroger distribution in a fixed bed pyrolysis of coals with different ranks:formation and source of N_2" Energy Fuels. 11. 477-482 (1997)

吴志恒：“不同等级煤固定床热解中氮气的分布：N_2的形成和来源”能源燃料。

Zhihengu Wu: "Nitrogen Distribution in a Fixed Bed Pyrolysis of coals with Different Ranks : Formation and Source of N_2" Energy Fuels. 11・2(印刷中). (1997)

吴志恒谷：“不同等级煤的固定床热解中的氮分布：N_2 的形成和来源”11・2（出版中）。

Yasuo Ohtsuka: "Effect of alkali and alkalire earth metals on nitrogen release during temperature programmed pyrolysis of coal" Fuel. 76(印刷中). (1997)

Yasuo Ohtsuka：“煤的程序升温热解过程中碱金属和碱土金属对氮释放的影响”Fuel 76（出版中）。

Zhiheng Wu: "Key fadrors for remarkable formation of N_2 from low roak coals during fixed bed pyrolysis:pyrolysis conditions and minerds" Energy Fuels. 11(印刷中). (1997)

吴志恒：“固定床热解过程中低粗煤显着形成 N_2 的关键因素：热解条件和矿工”能源燃料 11（出版中）。