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Questions tagged [catalysis]

This tag is appropriate for reactions, their mechanisms, their kinetics, when catalysts of any kind are involved.

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What is the mechanism of platinum as catalyst poisons on alumina?

I'm wondering if anyone knows by what mechanism is platinum (or other noble metals) catalyst on alumina substrate poisoned? Presently, I'm using platinum on alumina to decompose a hydrogen peroxide / ...
5
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2answers
39 views

Intuition for why catalyst affects both forward and reverse reactions equally?

I have looked for quite a long time on the site however all the answers involve mathematical explanations involving Arrhenius's equation. I would really like an intuitive reason (or one using ...
2
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0answers
15 views

Metal catalysts used in C-H bond functionalisation [on hold]

Why are the late transition metals used for C-H bond activation/functionalisation? What atomic properties of the late TM make them attractive for coordinating C-H sigma bonds? Thanks.
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0answers
9 views

How can alumina form spinel structure?

And many researchers have established the fact gamma alumina has a cubic defect spinel strucuture, but there is only one cation ie Aluminium in alumina, so how can it form spinel structure? Also ...
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0answers
15 views

Why does alpha alumina have less surface area than gamma alumina?

Its been documented extensively that when gamma alumina (cubic) changes into alpha alumina (hexagonal) at temperatures around 1200 °C the specific surface area reduces considerably. What are exact ...
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0answers
13 views

Why only barium and lanthanum are used for improving surface properties of alumina?

I read in a paper that the reason for enhanced surface properties of alumina after barium and lanthanum addition was that they didn't interact with the support by formation of oxide layer over the ...
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0answers
27 views

Improvement of the thermal stability of hydrous zirconia by post-synthesis treatment with NaOH and NH4OH solutions

I read a paper about how researchers improved the thermal stability of hydrous zirconia by post-synthesis treatment with $\ce{NaOH}$ and $\ce{NH4OH}$.[1] While the surface area of non-treated ...
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2answers
71 views

Using TBAI (tetra-butylammonium iodide) as a catalyst. Ideas on the mechanism or the driving force?

for my etherification of an alcoxide with alkylbromide I used TBAI as a catalyst. The catalyst transfers the alkylbromide into an alkyliodide which is more reactive. I was wondering, what is the ...
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1answer
84 views

Hydrogenation of 1-hexene with Raney nickel

For my high school senior chemistry project, I need to create and perform a lab. I've chosen to do the hydrogenation of 1-hexene with the catalyst of Raney nickel. I'm struggling because I'm not ...
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2answers
74 views

Why isn't iron (III) oxide an effective catalyst for decomposing hydrogen peroxide?

I've been working on a project involving the catalyst iron(III) oxide for decomposing hydrogen peroxide. It barely seemed to produce any oxygen. https://www.youtube.com/watch?v=Ta4DomSDzF8 This video ...
3
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1answer
73 views

Is it possible to convert methane and carbon dioxide to acetic acid?

Please forgive a bumbling amateur. I have been looking up bond strengths and it seems to me that it should be possible to combine methane with carbon dioxide to make acetic acid: $$\ce{CH4 + CO2 -&...
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0answers
37 views

Constraints on rate coefficients in chiral catalytic system

Consider some reversible chemical reaction in a closed system: $$\ce{A <=> B + D} \tag{1}$$ where $\ce{A}$ is some input reagent and $\ce{B}$, $\ce{D}$ are some output reagents. Let's denote ...
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1answer
77 views

How do catalysts provide alternative routes for reactions?

According to collision theory, a reaction will take place between, say, two molecules, if the collision between the atoms has a sufficiently high kinetic energy (to meet the activation energy ...
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0answers
38 views

Enantioselective alkylation of Aldehydes by Dialkylzinc reagents

Enantioselective catalysis is one of the important reactions in Organic chemistry which has huge applications in practical basis for synthesis of optically pure natural compounds. In this respect, I ...
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0answers
50 views

Why mixture turns brown upon heating, during esterification with H2SO4?

In the lab I was synthesising an ester with sulphuric acid as a catalyst. However the mixture turned brown and my teacher said I had burnt the acid, but what does this actually mean?
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35 views

Inert Catalyst for Luminol Chemiluminescence

I am trying to mix a solution of NaOH, luminol and a catalyst in order to detect hydrogen peroxide with chemiluminescence. However, I was unable to find a suitable catalyst for the detection solution. ...
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0answers
39 views

Meaning of electrochemical vs nonelectrochemical steps

Can someone please explain to me what is meant by an electrochemical reaction step and how it differs from a nonelectrochemical reaction step in the same overall reaction in the context of ...
3
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2answers
384 views

Rate of catalytic hydrogenation of alkenes

What does the rate of catalytic hydrogenation of alkenes depend upon? What'd be the increasing order of rate towards catalytic hydrogenation of the following alkenes, A (2-methylpropene), B (cis-but-2-...
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1answer
65 views

Are there any process and catalyst for convert CO2 and H2O into CH4 and O2 [duplicate]

The equation is simple $$\ce{CO2 + 2 H2O -> CH4 + 2 O2}$$ Yet, is it possible? Are there processes like heat, pressure, electricity, laser and/or any catalyst that could do this process directly? ...
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0answers
37 views

Extraparticle transport limitations in het. catalysis: Varying Damköhler without affecting the external prater number (and vice versa)

Solving a question for exam preparation; In the lecture script it is asked: 1. When both external MT and HT limitations exist, derive a solution from the general mass and energy balances in terms ...
4
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1answer
72 views

Two reactions that catalyze each other [closed]

Is there an example of two reactions that catalyze one another? More than two is also helpful, but I guess it will be hard to find one. By "catalyze one another", I mean that one of the products of ...
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0answers
28 views

Application of BET to micropore

'application of the BET equation should be restricted to the range where the term n(1 – p/p0) continuously increases with p/p0'see 5.2.2 in the reference This is one of the criterias IUPAC proposes ...
3
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1answer
213 views

How does calcium chloride act as a sequestrant (food science)?

This Wikipedia page lists common sequestrants (with respect to food science). As stated on the page: A sequestrant forms chelate complexes with polyvalent metal ions, especially copper, iron and ...
2
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0answers
96 views

What happens to promoters or poisons during a catalyzed reaction?

Catalysts are substances that influence reaction rates without undergoing changes in their mass and chemical composition, but may undergo physical changes. Promoters, poison etc. affect the activity ...
3
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1answer
430 views

Catalyst with zero order kinetics

I've read in a book that a catalyst may be included in the rate equation even though it is never used up. It was written as having zero order kinetics however I thought catalyst concentration will ...
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0answers
205 views

Catalytic poison in Pt catalysed manufacture of H2SO4

I came across a question that goes as: In manufacturing of sulfuric acid in presence of platinum catalyst, which metal impurity acts as a catalytic poison? Fe Cr Cu V I searched ...
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1answer
115 views

Shift in the position of equilibrium by a catalyst to favor the forward reaction

We were looking at the factors that affect dynamic equilibrium today. The teacher explained how catalysts only affect the rate at which dynamic equilibrium is achieved, and not its position. My ...
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0answers
921 views

What is the annelation effect?

My textbook had this question: Hydrogenation of napthalene with excess hydrogen gas stops cleanly at 1,2,3,4-tetrahydronapthalene. What conclusion can be drawn from this experiment? I observed ...
2
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1answer
1k views

What is the order of the catalytic decomposition of hydrogen peroxide?

I recently did an experiment to determine the activation energy of the decomposition of hydrogen peroxide using iron (III) chloride as a catalyst. I repeated this experiment at different temperatures. ...
2
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1answer
76 views

What causes the anti-siccative effect of soot (amorphous carbon) as a pigment in oil paints?

Oil paint containing carbon black (soot, charcoal) pigment is known to polymerize ("dry") a lot slower than if it has other pigments. I understand this is not just due to the absence of pigments which ...
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1answer
580 views

can a thermodynamically unfavorable reaction be made favorable by a catalyst?

The question i am asking about is pertaining simply to chemical use of a catalyst. It drives a reaction along a different path without taking part chemically. I know this fact. Is it possible so like ...
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0answers
39 views

Do catalysts themselves need an input of energy to work?

Do catalysts themselves need an input of energy to work? My book says "catalysts do not per se require an energy source". What does it mean by per se? If they don't use energy how do they activate?
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2answers
495 views

Choice of Lewis Acid for EAS reaction

Why is AlCl3 or FeCl3 might be preferred for chlorination reactions and AlBr3 or FeBr3 for bromination reactions? Why not use AlCl3 for bromination reactions? Source: https://www....
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2answers
583 views

How do I heat my borosilicate reflux column?

I am gonna use a ceramic tape heater, but cannot wrap it around evenly. Is the glass column gonna be okay? I am running some tests on plastic pyrolysis. I am using the reflux condenser to make the ...
4
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1answer
154 views

Why doesn't a catalyst shift the position of equlibrium, when temperature does?

Maybe this is a silly question, but it's not one I've been able to answer to my own satisfaction. Increasing the temperature of a reaction favours the endothermic direction, because it makes it ...
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1answer
258 views

Potential Energy Diagrams and the Effect of Catalysts [closed]

Why does a potential energy diagram showing the effect of a catalyst on activation energy not move left on the reaction pathway scale (compared to uncatalysed reaction) if a catalyst speeds up ...
3
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0answers
70 views

Role of Lewis acid in synthesis of adamantane from bicyclic species

What is the role of $\ce{AlCl3}$ in the following synthesis of adamantane? I'm guessing it functions as a Lewis acid, but I am unsure how the mechanism of the second step works, as there is no region ...
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0answers
38 views

Reaction Kinetics and Catalyst Addition

The addition of a catalyst is known to increase the rate constant of a reaction by providing an easier pathway for the reaction to occur, one with lesser activation energy. My doubt is: Is it ...
4
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1answer
316 views

Auto-catalysis Mechanism

I just read about the theory of auto-catalysis, and here's one thing which is sort of unclear to me: In this type of catalysis, one of the reaction product catalyses the reaction. For example, in ...
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0answers
62 views

What are some reactions which can be used to study “Effect of Catalyst on the Rate of Reaction”?

I wish to study the effect of catalyst on the rate of reaction as an investigatory project. What are some reactions and ideas that I could use to study this? One example to this is the decomposition ...
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0answers
231 views

Is there a catalyst for the decomposition for hydrogen peroxide that speeds it up but still makes the reaction light dependent?

I am building a Rube Goldberg machine for Science Olympiad, and one of the scoring steps is to use light to trigger a chemical reaction, which made me immediately think of the decomposition of ...
4
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0answers
36 views

Pd-catalysed hydrogenation of imines

Hydrogenation of imines to amines by $\ce{H2}$ on $\ce{Pd/C}$ has been used e.g. in the synthesis of Pumiliotoxin. By contrast, carbonyl groups are rarely reduced in this way, which I though was due ...
5
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3answers
559 views

Which diagram shows the effect of catalysis on chemical equilibrium?

My course book has the diagram in figure (1) to represent the effect of a catalyst on chemical equilibrium. I drew the second diagram in figure (2). When reviewing the diagram in figure (1), I ...
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1answer
146 views

Is there a direct relationship between the adsorption energy and the catalytic activty

I have seen in several papers, where people correlate adsorption energy with the catalytic activity; the greater the adsorption energy, the greater would be the catalytic activity. I understand that ...
0
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1answer
239 views

In an experiment testing catalyst influence on reaction, is NaOH a reactant or a catalyst? [closed]

I have recently completed an experiment with hydrogen peroxide (5%), 0.1M KI and 1M NaOH. Is the sodium hydroxide a reactant or a catalyst in this experiment?
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0answers
482 views

Rate order of decomposition of hydrogen peroxide

I have been having some troubles finding a source for my investigation. I am inverstigating the decomposition of hydrogen peroxide, which (according to my teacher/supervisor) is a second order ...
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1answer
124 views

What's the mechanism of water catalyzing a reaction of hydrogen sulfide gas and sulfur(IV) oxide to yield sulfur?

The reaction $$\ce{2 H2S(g) + SO2(g) -> 2 H2O(l) + 3 S(s)}$$ goes in presence of a catalyst, usually $\ce{Al2O3}$ or $\ce{TiO2}$, but also just in presence of moist or water (YouTube video) I ...
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2answers
404 views

Why aren't chaperones considered to be catalysts?

I'm reading about protein folding on Wikipedia and I stumbled on a bit about a class of proteins called chaperones that aid in the folding of proteins by: ...reducing possible unwanted aggregations ...
2
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1answer
105 views

Minimizing Catalyst Residue in Vegetable Oil Hydrogenation

We are using a nickel catalyst in our hydrogenation process to help convert vegetable oil to vegetable wax. The issue is ensuring all additives are successfully removed once hydrogenation is complete. ...
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1answer
275 views

What does it mean if a catalyst support is doped? [closed]

I have seen literature refer to catalyst supports being doped with another chemical, such as Nb doped $\ce{TiO2}$. What does it mean if a catalyst support is doped?