| 主权项 |
1. A method for synthesizing a DDR framework type zeolite, comprising:
forming a reaction mixture capable of forming crystalline DDR framework type material, the mixture comprising water, a silicon oxide, an alkali or alkaline earth hydroxide, and a methyltropinium salt structure directing agent, the mixture having a ratio of silicon oxide to hydroxide of about 0.01 to about 1.0, a ratio of silicon oxide to alkali and alkaline earth metal of about 0.01 to about 2.0, a ratio of silicon oxide to structure directing agent of about 0.01 to about 2.0, and at least about 0.05 wt % of seeds relative to the weight of the mixture; recovering DDR framework type crystals from the reaction mixture; converting the recovered DDR framework type crystals to their H-form, wherein the H-form DDR framework type crystals have an N2 BET surface area and a methane diffusivity; and steaming the H-form DDR framework type crystals at a temperature from 426° C. to 1100° C. for a time period from about 30 minutes to about 48 hours, so as to attain one or more of the following properties:
a CH4 diffusivity of no more than 95% of the CH4 diffusivity of otherwise identical but unsteamed H-form DDR framework type crystals;an N2 BET surface area from 85% to 110% of the N2 BET surface area of otherwise identical but unsteamed H-form DDR framework type crystals;following a pre-treatment at about 100° C., an equilibrium CO2 sorption capacity from 80% to 105% of the equilibrium CO2 sorption capacity of otherwise identical pre-treated but unsteamed H-form DDR framework type crystals; andfollowing a pre-treatment at about 400° C., an equilibrium CO2 sorption capacity from 80% to 105% of the equilibrium CO2 sorption capacity of otherwise identical pre-treated but unsteamed H-form DDR framework type crystals. |
