Characterization of ZrO2-SiO2 unmodified or modified with H2SO4 and acid catalysis

Sohn, Jong Rack; Jang, Hyang Ja

doi:10.1016/0304-5102(91)85143-p

Cited by 87 publications

(28 citation statements)

References 38 publications

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“…It was also observed that the phase transformation from tetragonal to monoclinic took place only beyond 550 o C in 5 wt.%SZ as compared to 450 o C in pure ZrO 2 . Many authors have reported the presence of either a tetragonal phase [17], or tetragonal along with monoclinic forms [18,19] in zirconia calcined below 450 o C. However, as evidenced from our XRD patterns, the tetragonal phase appeared to be more predominant.…”

Section: Resultscontrasting

confidence: 66%

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

Vishwanathan

Gajula

Rajesh

et al. 2007

React Kinet Catal Lett

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Section: Resultscontrasting

confidence: 66%

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

Vishwanathan

Gajula

Rajesh

et al. 2007

React Kinet Catal Lett

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“…45 Cumene dealkylation takes place on relatively strong acid sites of the catalysts. 42,43,46 Catalytic activity for cumene dealkylation against WO 3 content is presented in Figure 10, where reaction temperature is 400-450 o C. Comparing Table 1 and Figure 10, the catalytic activity is also correlated with the acidity. The correlation between catalytic activity and acidity holds for both reactions, cumene dealkylation and 2-propanol dehydration, although the acid strength required to catalyze acid reaction is different depending on the type of reactions.…”

Section: Resultsmentioning

confidence: 86%

“…The correlation between catalytic activity and acidity holds for both reactions, cumene dealkylation and 2-propanol dehydration, although the acid strength required to catalyze acid reaction is different depending on the type of reactions. 42,43 As seen in Figures 9 and 10, the catalytic activity for cumene dealkylation, in spite of higher reaction temperature, is lower than that for 2-propanol dehydration. To examine the promoting effect of NiO on the catalytic activities, the catalytic activities of NiO-TiO 2 /15-WO 3 for 2-propanol dehydration and cumene dealkylation are plotted as a function of NiO in Figures 11 and 12, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…It has been known that 2-propanol dehydration takes place very readily on weak acid sites. 42,43 Good correlations have been found in many cases between the acidity and the catalytic activities of solid acids. For example, the rates of both the catalytic decomposition of cumene and the polymerization of propylene over SiO2-Al2O3 catalysts were found to increase with increasing acid amounts at strength H 0 ≤ +3.3.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of NiO-TiO₂Modified with WO₃and Catalytic Activity for Acid Catalysis

2004

Bulletin of the Korean Chemical Society

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A series of NiO-TiO2/WO3 catalysts was prepared by drying powdered Ni(OH)2-Ti(OH)4 with ammonium metatungstate aqueous solution, followed by calcining in air at high temperature. Characterization of prepared catalysts was performed by using FTIR, Raman, XPS, XRD, and DSC and by measuring surface area. Upon the addition of tungsten oxide to titania up to 25 wt%, the specific surface area and acidity of catalysts increased in proportion to the tungsten oxide content due to the interaction between tungsten oxide and titania. Since the TiO2 stabilizes the tungsten oxide species, for the samples equal to or less than 25 wt%, tungsten oxide was well dispersed on the surface of titania, but for the samples containing above 25 wt%, the triclinic phase of WO3 was observed at calcination temperature above 400 o C. The catalytic activities of 10-NiO-TiO2/WO3 for 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method. NiO may attract reactants and enhance the local concentration of reactants near the acid sites, consequently showing the increased catalytic activities.

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“…4. IPA dehydration has been used by several authors35, 36 as a test reaction to determine the acidity of different catalysts and it proceeds quickly on weak acid sites 37. In the working conditions used, it was found that IPA reacts on the bare support and on the PWA supported catalysts selectively to propene.…”

Section: Resultsmentioning

confidence: 99%

Introduction to the Special Issue: JTRES 2009

Schoeberl

Higuera-Toledano

2011

Concurrency and Computation

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Java is a very successful language for several application domains: be it desktop applications, large enterprise server applications, web services, or applets for mobile phones. With the Real-Time Specification for Java (RTSJ) and the upcoming definition of a Safety-Critical Java profile, Java enters the domain of soft and hard real-time systems.The The RTSJ is the main standard for real-time systems implemented in Java. Several commercial and research implementations of the RTSJ are available today. However, the optimal implementation of some features of the RTSJ is still an open research questions. The primary goal for asynchronous event handlers (AEH) in the RTSJ is to have a lightweight concurrency mechanism. In the article, Applying Fixed-Priority Preemptive Scheduling with Preemption Threshold to Asynchronous EventHandling in the RTSJ [1], Kim and Wellings propose a scheduling scheme for AEH that minimizes the number of server threads needed. In the article they first define the worst-case scenario that demands the least upper bound of servers for self-suspending and non-self-suspending handlers. Based on the worst-case scenarios, it is proved that the number of servers required to execute a given number of non-self-suspending handlers depends on the number of priority levels, not on the number of handlers. It is also shown that each self-suspending handler is required to have its own server to prevent unbounded priority inversion.The RTSJ supports two kinds of real-time threads: one that can operate on the garbage collected heap and another one that avoids influence by garbage collection by using a region-based memory management. Basanta-Val et al. present in their article, Extending the concurrency model of the Real-Time Specification for Java [2], a more flexible thread model, where the thread can switch between a heap and a non-heap mode. The authors propose a simple extension to the current threading model named RealtimeThread++, in an attempt to introduce more flexibility in the RTSJ concurrency model. The article describes the extension from several points of view: (i) the programmer, identifying scenarios that may benefit from it significantly; (ii) the real-time Java technology perspective, identifying changes required in the current real-time virtual machine to support it; and (iii) the accumulated experience, relating empirical results obtained from a software prototype that supports the extension.The current practice for soft real-time systems in Java is to avoid the cumbersome programming model of scoped memories and, instead, use a real-time garbage collector. Kalibera presents in his article, Replicating , an incremental garbage collector. The realtime collector has to relocate objects in the heap to avoid fragmentation. This is usually achieved via an indirection that has to be followed on every read and write to the heap. Kalibera presents an alternative solution, based on object replication, which does not need any special handling for memory reads, but writes are more expensive: every va...

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Characterization of ZrO2-SiO2 unmodified or modified with H2SO4 and acid catalysis

Cited by 87 publications

References 38 publications

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

Characterization of NiO-TiO₂Modified with WO₃and Catalytic Activity for Acid Catalysis

Introduction to the Special Issue: JTRES 2009

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Characterization of ZrO2-SiO2 unmodified or modified with H2SO4 and acid catalysis

Cited by 87 publications

References 38 publications

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

Characterization of NiO-TiO2Modified with WO3and Catalytic Activity for Acid Catalysis

Introduction to the Special Issue: JTRES 2009

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Characterization of NiO-TiO₂Modified with WO₃and Catalytic Activity for Acid Catalysis