Модифицированый ионами меди (II) природный клиноптилолит в реакции низкотемпературного окисления диоксида серы
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Дата
2013
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Таврический национальный университет им. В. И. Вернадского
Анотація
Установлены закономерности низкотемпературного окисления диоксида серы кислородом в
присутствии CuX2 (X =Cl-, - 3 NO ), закреплённого на природном и предварительно активированном
клиноптилолите. Показано, что образцы проявляют разное время защитного действия от SO2,
продолжительность которого зависит от способа активирования клиноптилолита и содержания CuX2.
Каталитическое окисление SO2 кислородом с установлением постоянной концентрации диоксида серы
на выходе из реактора осуществляется в присутствии CuCl2-KCl/П-Кл композиции, включающей
дополнительно сокатализатор йодид-ион.
Встановлені закономірності низькотемпературного окиснення діоксиду сірки киснем у присутності CuХ2 (X =Cl - , NO - 3 ), закріпленого на природному і попередньо активованому клиноптилоліті. Показано, що зразки демонструють різний час захисної дії від SO2, тривалість якого залежить від способу активування клиноптилоліту і вмісту CuХ2. Каталітичне окиснення SO2 киснем з встановленням постійної концентрації діоксиду сірки на виході з реактора здійснюється в присутності композиції CuСl2-КСl-КІ/П-Кл, що вміщує співкаталізатор йодид-іон.
Samples of natural (N-CLI) and preliminary activated clinoptilolite were used in the work. The activation was carried out for 1 h by a hydrothermal (H2O-CLI) or an acid-thermal (H-CLI-1) or a thermal (300-CLI) method. Catalytic compositions were obtained by impregnation of the supports with solutions of CuX2 (X = - 3 NO , Cl - ) or CuCl2-KCl or CuCl2-KCl-KI with following drying of the impregnated samples at 100 °C till constant weight. The initial and modified samples were both characterized by their X-ray phase analysis and tested in the reaction of low-temperature oxidation of sulfur dioxide with air oxygen. Criteria of the activity both the sorbents and the catalyst based on them were such parameters: t0 – the period of time when there was no SO2 at the reactor outlet. tMPC – the period of time required for achievement of the maximum permissible concentration (MPCSO2 = 10 mg/m3) at the reactor outlet, n = Qexp/Qth – a stoichiometric parameter of the reaction, Qexp – the experimental amount of SO2 entered into the reaction, moles of SO2, Qth – the theoretical amount of SO2 calculated subject to both a copper(II) content in a sample and the stoichiometry of a reaction CuCl2 + SO2 + H2O = 2CuCl + H2SO4 + 2HCl It has been found that the samples of natural and activated clinoptilolite adsorb different amounts of SO2 and only thermally activated clinoptilolite (300-CLI) has protective properties (t0 = 50 min and tMPC = 70 min) at initial SO2 concentration of 150 mg/m3. After modification of the supports with copper(II) chloride (CCuCl2 = 2.9·10-4 mole/g) t0 and tMPC considerably increase and the modified supports can be placed in the following sequence: H2O-CLI (300 and 410) > H-CLI-1 (260 and 350) > 300-CLI (160 and 300) > N-CLI (70 and 160). The catalytic activity of the CuX2-modified samples (X = - 3 NO , Cl - ) in the reaction with SO2 depends on both a nature of the copper(II) salt and a copper(II) content. Cu(II) nitrate does not show catalytic properties and the amount of SO2 adsorbed decreases with the increase of Cu(NO3)2 content in the samples. It is caused by a blockage of a clinoptilolite surface. The increase of copper(II) chloride amount in the samples from 1.5·10-5 to 5.9·10- 5 mole/g results in fiftyfold multiplication of Qexp as compared with initial N-CLI. In spite of stoichiometric coefficient, n, is more than 1, the steady-state regime of SO2 oxidation with air oxygen does not set in and, after some period of time Сf SO2 becomes equal to Сin SO2 . The reaction kinetics changes sharply when iodide ions are inserted in CuCl2- KCl/N-CLI composition: SO2 concentration at the reactor outlet slowly increases after MPC attainment (tMPC = 300 min) and the steady-state regime (Сf SO2 = const) sets in. The stoichiometric coefficient. n, is more than 5 when the experiment is stopped in 750 min. It indicates that the process of sulfur dioxide oxidation is really catalytic. Thus, the conditions for really catalytic sulfur dioxide oxidation with air oxygen in the presence of clinoptilolite modified with copper(II) ions and halogenide ions (Cl - , I - ) have been found.
Встановлені закономірності низькотемпературного окиснення діоксиду сірки киснем у присутності CuХ2 (X =Cl - , NO - 3 ), закріпленого на природному і попередньо активованому клиноптилоліті. Показано, що зразки демонструють різний час захисної дії від SO2, тривалість якого залежить від способу активування клиноптилоліту і вмісту CuХ2. Каталітичне окиснення SO2 киснем з встановленням постійної концентрації діоксиду сірки на виході з реактора здійснюється в присутності композиції CuСl2-КСl-КІ/П-Кл, що вміщує співкаталізатор йодид-іон.
Samples of natural (N-CLI) and preliminary activated clinoptilolite were used in the work. The activation was carried out for 1 h by a hydrothermal (H2O-CLI) or an acid-thermal (H-CLI-1) or a thermal (300-CLI) method. Catalytic compositions were obtained by impregnation of the supports with solutions of CuX2 (X = - 3 NO , Cl - ) or CuCl2-KCl or CuCl2-KCl-KI with following drying of the impregnated samples at 100 °C till constant weight. The initial and modified samples were both characterized by their X-ray phase analysis and tested in the reaction of low-temperature oxidation of sulfur dioxide with air oxygen. Criteria of the activity both the sorbents and the catalyst based on them were such parameters: t0 – the period of time when there was no SO2 at the reactor outlet. tMPC – the period of time required for achievement of the maximum permissible concentration (MPCSO2 = 10 mg/m3) at the reactor outlet, n = Qexp/Qth – a stoichiometric parameter of the reaction, Qexp – the experimental amount of SO2 entered into the reaction, moles of SO2, Qth – the theoretical amount of SO2 calculated subject to both a copper(II) content in a sample and the stoichiometry of a reaction CuCl2 + SO2 + H2O = 2CuCl + H2SO4 + 2HCl It has been found that the samples of natural and activated clinoptilolite adsorb different amounts of SO2 and only thermally activated clinoptilolite (300-CLI) has protective properties (t0 = 50 min and tMPC = 70 min) at initial SO2 concentration of 150 mg/m3. After modification of the supports with copper(II) chloride (CCuCl2 = 2.9·10-4 mole/g) t0 and tMPC considerably increase and the modified supports can be placed in the following sequence: H2O-CLI (300 and 410) > H-CLI-1 (260 and 350) > 300-CLI (160 and 300) > N-CLI (70 and 160). The catalytic activity of the CuX2-modified samples (X = - 3 NO , Cl - ) in the reaction with SO2 depends on both a nature of the copper(II) salt and a copper(II) content. Cu(II) nitrate does not show catalytic properties and the amount of SO2 adsorbed decreases with the increase of Cu(NO3)2 content in the samples. It is caused by a blockage of a clinoptilolite surface. The increase of copper(II) chloride amount in the samples from 1.5·10-5 to 5.9·10- 5 mole/g results in fiftyfold multiplication of Qexp as compared with initial N-CLI. In spite of stoichiometric coefficient, n, is more than 1, the steady-state regime of SO2 oxidation with air oxygen does not set in and, after some period of time Сf SO2 becomes equal to Сin SO2 . The reaction kinetics changes sharply when iodide ions are inserted in CuCl2- KCl/N-CLI composition: SO2 concentration at the reactor outlet slowly increases after MPC attainment (tMPC = 300 min) and the steady-state regime (Сf SO2 = const) sets in. The stoichiometric coefficient. n, is more than 5 when the experiment is stopped in 750 min. It indicates that the process of sulfur dioxide oxidation is really catalytic. Thus, the conditions for really catalytic sulfur dioxide oxidation with air oxygen in the presence of clinoptilolite modified with copper(II) ions and halogenide ions (Cl - , I - ) have been found.
Опис
Ключові слова
диоксид серы, окисление, клиноптилолит, активирование, діоксид сірки, окиснення, клиноптилолит, активування, sulfur dioxide, oxidation, clinoptilolite, activation
Бібліографічний опис
Ученые записки Таврического национального университета им. В. И. Вернадского