Note: What follows assumes you have a reasonable idea about activation energy and its relationship with the Maxwell-Boltzmann distribution. This is covered on the introductory page about collision theory. If you aren't confident about this, follow this link, and use the BACK button on your browser to return to this page.
You can mark the position of activation energy on a Maxwell-Boltzmann distribution to get a diagram like this:. Only those particles represented by the area to the right of the activation energy will react when they collide. The great majority don't have enough energy, and will simply bounce apart. If there are very few particles with enough energy at any time, then the reaction will be slow. Important: I have already commented on this on the introductory page about collision theory and also on the page about the effect of temperature.
You mustn't get the idea that those particles in the blue area of the graph can never react. There are constant random collisions between the particles, and constant exchanges of energy between them. Some particles will gain energy in random collisions, and others will lose energy. So a low energy particle could, an instant later, have gained enough energy from a collision that it could now react.
And the opposite is true. A more energetic particle which didn't happen to collide successfully and produce a reaction, could find itself slowed down an instant later as a result of a collision. Because of this constant exchange of energy, given time all the particles will react if the reacting proportions are right.
To increase the rate of a reaction you need to increase the number of successful collisions. One possible way of doing this is to provide an alternative way for the reaction to happen which has a lower activation energy. As before, particles which don't have enough energy at a particular time will at some time in the future gain energy from random collisions, just as other particles will lose energy. You mustn't get the idea that those particles in the blue area of the graph can never react - given time they will.
The catalysts accelerate a reaction that converts synthesis gas a mixture of hydrogen and carbon monoxide into the hydrocarbon molecules that form GTL wax — the basis for the production of finished GTL products.
Advances in technology have been crucial to making the process work efficiently on a large scale. The catalysts are distributed throughout tens of thousands of tubes inside each 1,tonne reactor. They are replaced every few years, one reactor at a time to minimise the impact on production.
For Shell, the start-up of Pearl GTL was the culmination of more than three decades of research, the filing of around 3, GTL-related patents and the development of some of the world's most advanced cobalt synthesis catalysts. Our gas-to-liquids GTL technology uses natural gas instead of crude oil to make liquid fuels, base oils for lubricants and other high-quality products. The effect of a catalyst on the activation energy is shown on a chart called a reaction profile. This shows how the energy of the reactants and products change during a reaction.
Catalysts A catalyst is a substance that: increases the rate of a reaction does not alter the products of the reaction is not chemically changed or used up at the end of the reaction Only a very small mass of catalyst is needed to increase the rate of a reaction.
How catalysts work A catalyst provides an alternative reaction pathway that has a lower activation energy than the uncatalysed reaction.
0コメント