多孔白云石颗粒的孔径分布、催化能力和流化特性

摘要

Porous dolomite pellets are potential catalysts for the tar decomposition in biomass gasification process. In order to develop the fluidized bed reactor with porous dolomite particles,porous dolomite pellets of a radius in the range of (0.9 -2.5) mm and a length in the range of (4.1 -8.6) mm were prepared,and their pore size distribution .catalytic effect and fluidization properties were investigated. The results showed that the porous dolomite pellets had much larger porosity in the pore size range of (0.1 -10) 祄 in comparison with natural dolomite particles. Under the condition of a catalyst loading at 117 g, a temperature at 800 ℃. And a flow rate of carrier gas at 2 L ·min-1 ,99.3% of acetic acid was decomposed by the porous dolomite pellets, while acetic acid decomposition rate over natural dolomite particles was only 36.5%. Furthermore, the drag coefficient was determined and an empirical equation of incipient fluidizing velocity for the porous dolomite pellets was established.The incipient fluidizing velocity enhanced from 1.3 m ·s11 to 2.4 m ·s-1 when the equivalent diameter of porous dolomite pellets increased from 2. 7 mm to 6. 8 mm. The calculated values of incipient fluidizing velocity was consistent with the experimental values.%多孔白云石颗粒是一种适用于生物质气化焦油裂解的催化剂.为了开发多孔白云石颗粒流化床焦油裂解反应器,制备出半径(0.9～2.5) mm和长度(4.1 ～8.6) mm的圆柱形多孔白云石颗粒,测定了多孔白云石颗粒的内部孔径分布、催化能力和流化特性.结果表明,与天然白云石颗粒相比,多孔白云石颗粒孔径(0.1～10)μm的空隙率大幅增加.在催化剂用量117 g、温度800℃和载气流量2L·min -的条件下,乙酸在多孔白云石颗粒上的裂解率达99.3％,而天然白云石颗粒上裂解率仅为36.5％.求出了多孔白云石颗粒的曳力系数,建立了多孔白云石颗粒初始流化速率的经验公式.多孔白云石颗粒的当量直径从2.7mm增至6.8mm时,初始流化速率从1.3m·s-1升至2.4m·s-1,初始流化速率的计算值与测定值一致.