论文部分内容阅读
采用碱土金属(Mg,Ca,Sr,Ba)对NaY分子筛进行改性,并采用氮气物理吸附、X射线衍射、氨气及二氧化碳程序升温脱附等技术对样品进行了表征,考察了阳离子物种对NaY结构、表面酸碱分布等的影响,以进一步甄别影响催化剂活性的关键因素.结果表明,阳离子物种所引入的碱性位尤其是中强碱性位控制着丙烯酸的生成,而表面酸性位则影响乙醛的生成.当以钡含量为2%的NaY分子筛为催化剂,在乳酸进料浓度为38%,进料空速为3h-1及325°C反应条件下,丙烯酸收率最高,为44.6%.这归结于该催化剂表面具有最多的中强碱性位,且表面Ba2+簇具有合适的Ba-O键长及碱度.
NaY zeolite was modified by alkaline earth metal (Mg, Ca, Sr, Ba). The samples were characterized by physical adsorption of nitrogen, X-ray diffraction, ammonia and carbon dioxide temperature-programmed desorption. NaY structure and surface acid-base distribution were investigated in order to further identify the key factors affecting the catalyst activity.The results showed that the basicity introduced by cationic species, especially the strong basicity, controlled the formation of acrylic acid, while the surface acidity Affecting the formation of acetaldehyde.When NaY zeolite containing 2% barium was used as catalyst, the yield of acrylic acid was the highest under the reaction conditions of lactic acid feed concentration of 38%, feed space velocity of 3h-1 and 325 ° C 44.6% .This is attributed to the catalyst surface has the most of the strong alkaline sites, and the surface Ba2 + cluster has the appropriate Ba-O bond length and alkalinity.