A catalyst provides an alternative reaction pathway with a lower activation energy. It does not change the shape of the Boltzmann distribution, because the temperature and the energies of the particles stay the same.On the Boltzmann distribution curve, the activation energy line moves to the left when a catalyst is used.The area under the curve to the right of the new, lower activation energy is larger. This means a greater proportion of particles have energy greater than or equal to the activation energy.More collisions are successful in a given time, so the rate of reaction increases. The catalyst itself is not used up and can be reused.