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Induction period
About: Induction period is a research topic. Over the lifetime, 2263 publications have been published within this topic receiving 50234 citations.
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TL;DR: The experimental results showed that lower pH value and CMP concentration brought faster degradation rate, and the possible mechanistic steps of CMP degradation were proposed.
496 citations
TL;DR: In this article, the initial temperature distribution in a reacting mixture enables one to calculate the induction period to the adiabatic explosion in each particle of the mixture, and the inverse gradient of this induction period determines the propagation velocity of the intensive reaction zone.
472 citations
TL;DR: In this article, a 2 wt% Mo/ZSM-5 catalyst was used for the dehydroaromatization of methane to benzene in the absence of an added oxidant.
448 citations
TL;DR: In this article, the effects of structure on reactivity during hydrosilation in homogeneous solutions of platinum catalysts, and point out similarities and differences that are observed with other catalysts.
Abstract: Publisher Summary This chapter describes numerous ways in which soluble complexes of transition metals act as catalysts for the hydrosilation of organic compounds, especially substituted and unsubstituted unsaturated hydrocarbons. The term “hydrosilation” can be used to describe an addition reaction in which compounds with one or more Si–H bonds add to any reagent. The chapter focuses on the effects of structure on reactivity during hydrosilation in homogeneous solutions of platinum catalysts, and point out similarities and differences that are observed with other catalysts. Commonly, when chloroplatinic acid is the source of the catalyst for hydrosilation and sometimes when salts of other metals are used, no effect is observed for some time after it has been added to a mixture of reagents. Then, rather suddenly a rapid reaction can ensue. This “induction period” can in some cases last for a relatively long time, even for hours. An induction period, followed by a very fast exothermic reaction leads to difficult situations when large amounts of reagents are employed. Homogeneous catalysis with metals other than platinum and hydrosilation of acetylenes is also discussed in this chapter.
435 citations
TL;DR: A mechanistic model for the induction, nucleation and growth for AB decomposition leading to formation of hydrogen is proposed, which yields a mobile phase of AB caused by disruption of the dihydrogen bonds and nucleation that yields reactive DADB from the mobile AB.
Abstract: The mechanism of hydrogen release from solid state ammonia borane (AB) has been investigated via in situ solid state 11B and 11B{1H} MAS-NMR techniques in external fields of 7.1 T and 18.8 T at a decomposition temperature of 88 °C, well below the reported melting point. The decomposition of AB is well described by an induction, nucleation and growth mechanistic pathway. During the induction period, little hydrogen is released from AB; however, a new species identified as a mobile phase of AB is observed in the 11B NMR spectra. Subsequent to induction, at reaction times when hydrogen is initially being released, three additional species are observed: the diammoniate of diborane (DADB), [(NH3)2BH2]+[BH4]−, and two BH2N2 species believed to be the linear (NH3BH2NH2BH3) and cyclic dimer (NH2BH2)2 of aminoborane. At longer reaction times the sharper features are replaced by broad, structureless peaks of a complex polymeric aminoborane (PAB) containing both BH2N2 and BHN3 species. The following mechanistic model for the induction, nucleation and growth for AB decomposition leading to formation of hydrogen is proposed: (i) an induction period that yields a mobile phase of AB caused by disruption of the dihydrogen bonds; (ii) nucleation that yields reactive DADB from the mobile AB; and (iii) growth that includes a bimolecular reaction between DADB and AB to release the stored hydrogen.
341 citations