前者的缩合形成了Lewis酸中心,而后者形成了Bronsted酸中心。2.3影响SO42-/ZrO2性质的因素2.3.1SO2-/ZrO比表面积42缪长喜28研究了沉淀温度、锆盐溶液浓度、PH值、加料方式及老化时间等因素对ZrO2比表面积的影响,提出降低沉淀温度和提高沉淀溶液的pH值均有利于提高ZrO2比表面积。Corm%认为,随沉淀溶液pH值的提高,ZrO2...
Comparing with SO42-/SnO2, in SO42-/SnO2-Al2O3 the intensity of attached-on-surface sulfuric groups is increased, the amount of effective acid is enhanced and the strengths of Brǒnsted and Lewis acid sites are improved. The TG results reveal that the aluminum could impr...
表明催化剂表面 有含硫物种存在 [3] ,能诱导产生强酸中心;催化剂 吸附吡啶后在l600~l400cm l 范围内的Ft-IR光 谱图中l450cm l 处无吸收峰,可见催化剂表面没 有Lewis酸性位;在l538cm l 处有一中强吸收峰, 此峰对应于表面的Br ns ed酸性位 [4] 。 2.l.2催化剂的XRD分析用SO 4 2 -M O 3 -...
在这些固体超强酸中,第①类固体超强酸,由于A1C13,SbF3等Lewis酸与载体之间的结合主要依靠化学和物理吸附作用而未形成化学键,使其在使用过程中活性组分易脱离载体失去超强酸的性质:而②、④、⑥类固体超强酸多含有卤离子,对设备腐蚀严重:第⑤类固体超强酸的酸强度相对于第③SO42-/MxOy型固体超强酸较弱[8]。 第...
一般特性 公式KCr(SO₄)₂ Structure of Chrome Alum Oxidation Numbers of KCr(SO₄)₂ Lewis Structure of KCr(SO4)2 [K]OS(=O)(=O)O[Cr]1OS(=O)(=O)O1 [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[K+].[Cr+3]
[18]对SO42-/MxOy吸附吡啶的红外光谱研究表明:无水样品的表面主要为Lewis酸位,吸水后Lewis酸位以1:l的比例向Bronsted酸位转化,其酸位结构可假设为图2-3所示: 图2-3 Lewis酸位和Bronsted酸位的相互转化 2.2 SO42-/ZrO2超强酸中心结构性质 为了揭示SO42-/ZrO2的强酸性,大量的研究工作集中于揭示固体酸的结构...
It was found that anhydrous CuSO4 served as critical Lewis catalyst28 for the conversion of ribonolactone to 2,3-O-isopropylidene-d-ribonolactone. Although relatively high yield (72%) was achieved, the CuSO4 is hard to be fully recovered due to its excellent solubilty in water. Marek Marczews...
-workers [12] also reported synthesis and characterization of the Al-MCM-41, wherein incorporation of an excess of aluminum formed an impure crystal-phase tridimite, and the Lewis acid site prevailed because of the octahedral non-framework aluminum, accompanied with the collapse of the structure....
At higher pressures, such as those required for carbon sequestration, gases no longer behave ideally and effective pressure, or fugacity (ƒ) must be used in place of partial pressure; fugacity is the tendency of CO2 molecules to escape into the solution (Lewis, 1901). CO2-phase fugacity ...
Lewis acidity experimentally showed by IR observation ofpyridine absorbed on it.XPS and AES techniques were employed to examine the valence states of tungsten,zirconium,sulfur and their interactions.The structure of sulfur species was studied by infrared spectroscopyand a structure model of active site...