Induction of catalytic activity by neutron irradiation of silica and silica-alumina

Mikovsky, R.J.; Weisz, Paul B.

doi:10.1016/0021-9517(62)90062-3

Cited by 5 publications

(5 citation statements)

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“…When it comes to catalytic applications of neutron irradiated materials, there are very few publications that report on the neutron radiation effect of oxide catalysts. Depending on the catalyst system, both positive and negative influences of the irradiation treatment on the catalytic activity have been reported. − However, neutron irradiation induced modifications of zeolites have gained no attention so far when it comes to the irradiation effect on the catalytic properties of the materials.…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the catalyst system, both positive and negative influences of the irradiation treatment on the catalytic activity have been reported. [37][38][39][40] However, neutron irradiation induced modifications of zeolites have gained no attention so far when it comes to the irradiation effect on the catalytic properties of the materials.…”

Section: ' Introductionmentioning

confidence: 99%

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Enhanced Catalyst Performance of Zeolite SSZ-13 in the Methanol to Olefin Reaction after Neutron Irradiation

et al. 2011

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Postsynthesis treatments are frequently used as a means of improving the performance of zeolitic catalysts. This study is concerned with the postsynthesis modification of zeolite H-SSZ-13 by neutron irradiation. An enhanced catalytic activity in the methanol to olefin (MTO) reaction is observed after neutron irradiation of the zeolite H-SSZ-13 catalyst. The magnitude of the neutron irradiation effect depends on the irradiation time and the Si/Al ratio of the parent material, as the highest increase in catalytic activity was observed for the irradiated high silica H-SSZ-13. FT-IR measurements with CO as a probe molecule revealed no significant change in the nature of the acid sites, and the acid strength of the catalytically important Brønsted acid sites was maintained after irradiation. Nitrogen physisorption measurements indicated a decrease in specific surface area and pore volume after neutron irradiation, whereas XRD confirmed that the crystallinity was maintained. The water content was found to be lower in the irradiated material, indicating an altered environment within the zeolite voids after irradiation. EPR measurements clearly showed the formation of radicals in consequence of the irradiation procedure. These radicals have been found to be stable in air, in daylight, and after heating to the MTO reaction temperature, and they were still detectable two years after irradiation. We suggest that the radical species consist of peroxy radicals (Si−O−O*) and nonbridging oxygen hole centers (NBOHC: ≡Si−O*) that are formed due to irradiation-induced bond rupture, and we further suggest that radiation-induced structural defects are responsible for the altered catalytic properties of zeolite H-SSZ-13.

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Section: Introductionmentioning

confidence: 99%

Section: ' Introductionmentioning

confidence: 99%

Enhanced Catalyst Performance of Zeolite SSZ-13 in the Methanol to Olefin Reaction after Neutron Irradiation

et al. 2011

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The effect of various types of irradiation, such as «-particles, neutrons, and -rays on the activity of catalysts (Coekelbergs et al, 1962;Mikovsky and Weisz, 1962;Taylor, 1965; Taylor, 1968; Weisz and Swegler, 1955) is reported. In these studies the catalytic activity increased significantly with the radiation treatment.

…”

mentioning

confidence: 99%

“…In all cases the commercially available catalyst was irradiated. Usually, fairly large dosages of irradiation were required to produce significant changes in the catalytic activity (Mikovsky and Weisz, 1962).Recently, another type of irradiation, ultrasonics, was used to increase the activity of a catalyst (Li et al, 1964; Ranganathan et al, 1971). The ultrasonic treatment (insonation) was carried out during the manufacture of the catalyst as opposed to the irradiation of the commercially available catalyst.…”

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Promises for Ultrasonic Waves on Activity of Silica Gel and Some Supported Catalysts

Ranganathan¹,

Mathur²,

Bakhshi³

et al. 1973

Product R&D

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The effect of various types of irradiation, such as «-particles, neutrons, and -rays on the activity of catalysts (Coekelbergs et al., 1962;Mikovsky and Weisz, 1962;Taylor, 1965; Taylor, 1968; Weisz and Swegler, 1955) is reported. In these studies the catalytic activity increased significantly with the radiation treatment. In all cases the commercially available catalyst was irradiated. Usually, fairly large dosages of irradiation were required to produce significant changes in the catalytic activity (Mikovsky and Weisz, 1962).Recently, another type of irradiation, ultrasonics, was used to increase the activity of a catalyst (Li et al., 1964; Ranganathan et al, 1971). The ultrasonic treatment (insonation) was carried out during the manufacture of the catalyst as opposed to the irradiation of the commercially available catalyst. The information reported in the literature is as yet too scant to afford a clear picture of the subject. The situation is made complex by the several variables in the case of irradiation with ultrasonics-the frequency, intensity, duration of insonation, and the atmosphere over the catalyst system during irradiation.The literature on insonation of catalysts can be divided in three categories: (I) insonation of the catalyst during the preparation stage; (II) insonation of the already prepared catalyst; and (III) insonation of the reaction mixture (including the catalyst). Two of these systems have been discussed in detail in one of our earlier papers (Ranganathan et al., 1971). A brief introduction is in order. Case I: Insonation of Catalyst during Preparation StageThe catalyst is insonated during the preparation stage. As the ultrasonics produce cavitation and mixing at the microlevel, insonation affects the catalyst particle size, crystallite size, pore size, and the pore-size distribution (Kapustin, 1962;Li et al., 1964;Slaczka, 1964).

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Acid and Base Centres: Their Structure and Acid-Base Properties

Tanabe

1970

Solid Acids and Bases

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Induction of catalytic activity by neutron irradiation of silica and silica-alumina

Cited by 5 publications

References 5 publications

Enhanced Catalyst Performance of Zeolite SSZ-13 in the Methanol to Olefin Reaction after Neutron Irradiation

Enhanced Catalyst Performance of Zeolite SSZ-13 in the Methanol to Olefin Reaction after Neutron Irradiation

Promises for Ultrasonic Waves on Activity of Silica Gel and Some Supported Catalysts

Acid and Base Centres: Their Structure and Acid-Base Properties

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