吸液驱气法指导变压吸附空分用碳分子筛制备

Spontaneous liquid-gas imbibition to guide preparation of carbon molecular sieve for air separation by pressure swing adsorption

碳分子筛(CMS)生产工艺流程长,工艺参数多,现行变压吸附(PSA)评测手段仅能提供最终产品信息,对指导CMS制备存在局限性,而吸液驱气法(SLGI)则能快速有效地表征不同生产阶段CMS样品孔隙的变化。以椰壳预炭化料为骨料,酚醛树脂为粘结剂制备了空分制氮用CMS。以H_(2)O为液体探针,N_(2)和SF_(6)为气体探针,考察了CMS制备过程中炭化、活化和沉积阶段样品的吸液驱气行为。结果表明:吸H_(2)O驱N_(2)速率和驱SF_(6)速率在不同分子尺寸范围反映了不同样品的孔径大小;N_(2)和SF_(6)的平衡驱气量在不同分子尺寸范围反映了不同样品的孔容大小。SLGI对不同条件下制备的CMS中间产品具有显著区分度,宜用于指导CMS生产。

The production of carbon molecular sieve(CMS)involves a series stages and is influenced by many parameters.The pressure swing adsorption(PSA)method has limitations to guide the preparation of CMS because it provides only the information of the final CMS product.Alternatively,the spontaneous liquid-gas imbibition(SLGI)makes it possible to quickly and effectively characterize the changes in the pores of CMS samples in the production process.In this study,coconut shell char was used as carbon precursor and phenol formaldehyde resin as binder to prepare CMS for air separation by PSA to produce N_(2).With H_(2)O as liquid probe and both N_(2) and SF_(6) as gas probes,the SLGI behaviors of the samples during the carbonization,activation and carbon deposition stages of the CMS preparation process were investigated.The results show that the rates of spontaneous H_(2)O-N_(2) imbibition and spontaneous H_(2)O-SF_(6) imbibition are dependent on the pore size of different samples in different molecular size ranges.The equilibrium gas displacements of N_(2) and SF_(6) reflect the pore volume of the samples in different molecular size ranges.The SLGI can characterize pore structure of intermediate products of CMS prepared under different conditions,which could be used to guide the production of CMS.