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91.
以高活性高稳定性的高稀土含量超稳改性分子筛为活性组元开发了新型重油催化裂化催化剂HSC-1,并利用XRF、BET、孔体积、磨损指数、粒度测定等对其化学组成及物化性能进行了分析,利用轻油微反及ACE对催化裂化性能进行了考察。结果表明,制备的催化剂HSC-1具有物化性能好、重油裂化能力及抗金属污染能力强、产物分布好、焦炭选择性及汽油选择性好,以及优异的降低汽油烯烃含量的特性。 相似文献
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以γ-Al2O3、VO2和V2O5为催化剂,在连续固定床微反装置上、500℃下,考察了噻吩在常压下的脱硫反应过程,并进行了噻吩原位吸附红外光谱、XPS光电子能谱、XRD等表征。结果表明,在催化裂化反应条件下,采用具有单纯L酸中心的催化剂时,噻吩脱硫反应的转化率很低;采用具有单纯氧化-还原中心的催化剂时,噻吩可被氧化成CO、CO2及SO2,但转化率也较低;采用既具有酸中心又具有氧化 还原中心的V2O5时,由于酸中心和氧化-还原中心的协同作用,噻吩脱硫反应的转化率最高,H2S和SO2的产率也最高。催化裂化反应条件下,噻吩可以被钒氧化物的晶格氧氧化,同时V2O5与VO2失去部分晶格氧被还原为V2O3等低价态产物;由于V2O5比VO2活泼晶格氧数目多,较易被还原,因此噻吩脱硫反应的SO2产率更高。V2O5表面存在的L酸中心Vn+-O-V为噻吩的初始吸附中心,L酸中心与临近的V=O双键的作用促进了噻吩的氧化。 相似文献
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In this paper,the different influences of lanthanum (La) and cerium (Ce) species on the stability of Y zeolite were studied by X-ray diffractometry (XRD),X-ray photoelectron spectroscopy (XPS),and multinuclear (27Al,29Si) solidstate nuclear magnetic resonance spectroscopy (NMR).It was found that the stability of Y zeolite could be enhanced by the introduction of La or Ce species;however,the former effect was more remarkable than the latter.These results were also confirmed theoretically by density functional calculations.There was a strong interaction between the rare earth (La or Ce) species and Y zeolite clusters,which restrained the formation of extra-framework aluminum and enhanced evidently the stability of Y zeolite.Furthermore,the interaction between La species and Y zeolite was stronger than that of Ce species with Y zeolite. 相似文献
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Effects of vanadium on light olefins selectivity of FCC catalysts were investigated with vanadium having different oxidation numbers(hereinafter abbreviated as Oxnum).Molecular modeling studies showed that vanadium with low Oxnum could affect the chemical conversion of large-size hydrocarbon molecules.However,the vanadium deposited on equilibrium catalyst had high Oxnum because of the oxidation reaction taking place in the regenerator,so an activation method to reduce vanadium Oxnum named "selective activation" was introduced.It was proved by means of Electron Paramagnetic Resonance(EPR) and Temperature-Programmed Reduction(TPR) methods that the vanadium Oxnum was decreased,when the catalyst was activated.The molecular modeling studies are consistent well with the lab evaluation results.The light olefins selectivity of activated equilibrium catalysts was better than that achieved by the inactivated catalysts.Similar results were observed with the lab vanadium-contaminated catalyst.The light olefins selectivity of the catalyst was optimized when the vanadium Oxnum was close to 2(VO). 相似文献
96.
烃分子尺寸及其与扩散能垒关系的初步研究 总被引:1,自引:0,他引:1
依次采用分子力学、分子动力学、量子力学方法计算得到烃分子的最低能量构象,获得了分子的三维尺寸,并与动力学直径进行了对比分析,并初步研究了烃分子尺寸与在 MFI、FAU 分子筛中扩散能垒的关系。结果表明,在分子筛催化研究中用三维尺寸描述烃分子大小比用动力学直径更合理。与环烷烃、芳烃分子相比,长链烷烃分子结构柔性较大,长链烷烃分子尺寸不能只考虑其最低能量构象的尺寸,还应考虑分子构象的动力学变化。在同一分子筛中,随烃分子最小截面尺寸的增加,扩散能垒增大;同一分子在 MFI 分子筛中的扩散能垒大于在 FAU 分子筛中的扩散能垒。研究结果对于探索分子筛择形催化机理具有一定的理论价值。 相似文献
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以基本遗传算法为基础,引入多重退火交叉,并以多种变异模式竞争取代单一的变异策略,以随着遗传代数和个体适应度动态调节的交叉和变异概率代替固定不变的交叉和变异概率,提出了一种改进的遗传算法;用于研究包含复杂组分、同时进行多种反应的催化裂解反应集总动力学,并与传统的算法比较,证明改进的遗传算法可迅速、准确获得有物理意义的动力学参数优化值,是研究复杂反应动力学的有效数值工具. 相似文献
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