摘要
低硅铝比X分子筛(LSX)经锂改性后因具有较高的N_(2)吸附量和氮氧分离系数,在变压吸附(PSA)领域具有广泛的应用,但合成LSX分子筛的原料价格逐年上涨,导致其生产成本居高不下。钾长石(KAlSi_(3)O_(8))富含氧化铝和氧化硅,钾还可以作为LSX分子筛的结构导向剂,是合成LSX分子筛的理想原料,可大大降低其生产成本。以嵩县钾长石为原料,经高温煅烧活化,加入晶种导向剂,采用导向剂法合成出了LSX分子筛,考察了硅铝比[n(SiO_(2))/n(Al_(2)O_(3))]、碱硅比n[(Na_(2)O+K_(2)O)/n(SiO_(2))]、水碱比[n(H_(2)O)/n(Na_(2)O+K_(2)O)]、晶种导向剂用量(w_(SDA))、晶化温度(T_(cry))、晶化时间(tcry)等对产物结构和性能的影响。结果表明,当n(SiO_(2))/n(Al_(2)O_(3))=2.1~2.2,n(Na_(2)O+K_(2)O)/n(SiO_(2))=2.0~2.2,n(H_(2)O)/n(Na_(2)O+K_(2)O)=35~45,w_(SDA)=3%~5%,T_(cry)=90~100℃,tcry=10~14 h,所得LSX分子筛结晶度较高,颗粒大小为5~8μm,Li^(+)最大交换度可达98.7%,达到了工业上氮氧吸附分离所需的条件(Li^(+)交换度大于96%)。
Low silicon aluminum ratio X molecular sieve(LSX)modified by lithium is widely used in the field of pressure swing adsorption(PSA)due to its high N_(2)adsorption capacity and nitrogen-to-oxygen separation ratio.However,the price of raw materials for the LSX synthesis increases,resulting in a higher production cost.Potassium feldspar(i.e.,KAlSi_(3)O_(8))is rich in aluminum oxide and silicon oxide,and potassium can also be used as a structural guide agent for LSX as an ideal raw material that can greatly reduce the production cost for the LSX synthesis.LSX was synthesized by using seed crystal as a guiding agent with a potassium feldspar from Songxian,China as a raw material,which was firstly calcined and activated at a high temperature.The effects of silicon aluminum ratio(n(SiO_(2)/n(Al_(2)O_(3))),alkali silicon ratio(n(Na_(2)O+K_(2)O)/n(SiO_(2)),water alkali ratio(n(H_(2)O)/n(Na_(2)O+K_(2)O)),amount of seed guide agent(ωSDA),crystallization temperature(T_(cry)),and crystallization time(tcry)on the structure and properties of samples were investigated.The results show that when n(SiO_(2))/n(Al_(2)O_(3))=2.1–2.2,n(Na_(2)O+K_(2)O)/n(SiO_(2))=2.0–2.2,n(H_(2)O)/n(Na_(2)O+K_(2)O)=35–40,ωSDA=3%–5%,T_(cry)=90–100℃,tcry=10–14 h,the obtained LSX molecular sieve has a high crystallinity,and a uniform morphology,and the exchange degree of Li^(+)can reach 98.7%,which obtain the properties for nitrogen and oxygen adsorption separation in industry.
作者
韩志远
勾明雷
陈紫宛
段永华
刘振
HAN Zhiyuan;GOU Minglei;CHEN Ziwan;DUAN Yonghua;LIU Zhen(School of Chemistry and Chemical Engineering,Henan University of Science and Technology,Luoyang 471023,Henan,China)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2023年第11期2978-2985,共8页
Journal of The Chinese Ceramic Society
基金
河南科技大学博士科研基金项目(4008-13480049)
河南省重点攻关项目(182102310795)。
关键词
钾长石
高温活化
晶种导向剂
低硅铝比分子筛
离子交换
potassium feldspar
high temperature activation
seed guide agent
low silicon aluminum ratio zeolite
ion exchange
