Пористі керамічні адсорбенти низькотемпературного випалу на основі синтетичних NaA і NaX цеолітів

Abstract

Дисертаційна робота присвячена розробленню основ технології синтезу штучних цеолітових мінералів структурних типів А (LTA) та X (FAU) з вітчизняної каолінової сировини високого ступеня кристалічності шляхом направленого керування процесами гідротермального синтезу та отримання на їх основі гранульованих адсорбційних матеріалів за рахунок використання комплексних додатків, що забезпечують необхідні адсорбційні та експлуатаційні властивості. Встановлено умови одержання гранульованих цеолітокерамічних адсорбентів за рахунок виявлених закономірностей формування їх структури і фазового складу. Визначено оптимальні склади мас в системі “цеоліт – глина – флюс –клітковина”, що дозволило отримати цеолітокерамічні адсорбенти з високими показниками пористості при дотриманні ними прийнятних міцнісних характеристик. Показано можливість керованого регулювання порової структури розроблених адсорбентів за рахунок введення в склад сировинної маси мезопористого синтетичного гідроксиапатиту та зміни співвідношення інгредієнтів суміші. Здійснено промислову апробацію розроблених цеолітовмісних адсорбентів. Диссертационная работа посвящена разработке основ технологии синтеза искусственных цеолитовых минералов структурных типов А (LTA) и X (FAU) с отечественного каолинового сырья высокой степени кристалличности путем направленного управления процессами гидротермального синтеза и получения на их основе гранулированных адсорбционных материалов за счет использования комплексных приложений, обеспечивающих необходимые адсорбционные и эксплуатационные свойства. Установлены условия получения гранулированных цеолитокерамических адсорбентов за счет выявленных закономерностей формирования их структуры и фазового состава. Определены оптимальные составы масс в системе "цеолит - глина - флюс - клетчатка", что позволило получить цеолитокерамические адсорбенты с высокими показателями пористости при соблюдении ими приемлемых прочностных характеристик. Показана возможность управляемого регулирования поровой структуры разработанных адсорбентов за счет введения в состав сырьевой массы мезопористого синтетического гидроксиапатита и изменения соотношения ингредиентов смеси. Осуществлено промышленную апробацию разработанных цеолитосодержащих адсорбентов. Thesis is devoted to the elaboration of basis of synthesis technology of artificial zeolite minerals of structural types A (LTA) and X (FAU) on the basis of national kaolin raw materials of high level of crystallinity and selection of efficient ways to attain on their base granulated adsorbent materials with specified structure parameters. The optimum conditions of kaolin thermo-preparation have been determined, which allows receiving zeolite products with high qualitative and quantitative characteristics during hydrothermal synthesis. The kinetic regularities of the zeolite forming processes in reactionary systems on the basis of kaolin burning products at the temperature of 800 C have been obtained. It has been researched that there is a possibility to attain granulated zeolite-fitting materials by methods of in situ crystallization in silica-alumina matrix and by conventional ceramic technology using clay binder. As a result of the research, it has been identified that the method of crystallization of zeolite phases in situ in beforehand formed and fired kaolin granules is not effective, inasmuch as after the final stages of synthesis the received materials have low water repellency. Moreover, it has been denoted that there is low quantitative content of zeolite as well as noticeable decline of permeability in granules. Due to detected technological limitations of the crystallization method in situ, the preference was given to the technology of granulation of synthesized zeolite powders with the help of binding agents. As a main component for binding fine crystal zeolites of NaA and NaX types, highly plastic clay of the area of Tchasov-Jarskiy deposits has been used. Due to the disposition of the clay to create densely sintered structure, and considering danger of screening the surface of zeolite crystals by its particles, the set of measurements to change its properties has been used with the help of additional components’ utilization. The optimum content of clay binder has been ascertained; which is modified by porous-forming and additives, thus, it allowed elaborating of the forming masses from which firing at the temperature not higher than the limits of temperature stability of zeolite phases, granulated zeolite ceramic adsorbents have been obtained with high indicators of porosity and necessary mechanical strength. Using standardized methods in ceramic technology to control structural physical and physico-mechanical parameters, the optimum conditions of modification of binding agent and its correlation with the zeolite component have been determined which allow to get the adsorbent with the proper parameters of firmness, sorbing capacity and porosity. According to the data of electronic microscopy of the composites of optimum composition the following has been specified: their structure belongs to the corpuscular type and represented by the individual crystals and units of zeolite phase which are linked between each other with the help of fragments of porosities clay binding. The results of low temperature adsorption of nitrogen indicate that the formation while smelting highly porous materials with the highly specific area and predominance of pores of the two groups of denomination: micropores and macropores. Hence, received materials thanks to the obvious sorbing properties and inherent to the zeolite phase of molecule sieve effect, can be used in the range of selective adsorbing processes, such as division of carbohydrate mixtures, deeply drying of gases and others. The conducted researches are directed to improve the efficiency of elaborated zeolite ceramic adsorbents at the expense of creation of the cavities of mesoporous denomination at the volume of their porous system. The possibility of controlled regulation of porous system of elaborated adsorbents has been proved at the expense of introducing raw material masses of mesoporous synthetic hydroxyapatite in the content and changes in correlation of ingredients of the mixture. According to the results of the studies, the researching industrial set of zeolite ceramic adsorbents has been released. Industrial approbation went through starting from technological greases during the water refinement. Elaborated adsorbents were used as adsorbent material for refining protein environment in education process at Lviv National University of Ivan Franko; cation-exchangers while water purification process and stationary phases for gas chromatography at the departments of analytical chemistry and hydraulics and plumbing at Lviv Polytechnic National University.