The temperature must be controlled, because if the high temperature caused coke and catalytic cause loss of.Products that do not need. Or potentially dangerous and damaged reactors.
If you need to control the temperature, high temperature will make the coke and the catalyst loses its ability to achieve product unwanted or potentially dangerous and cause damage to the reactor.
To control the temperature of high temperature will occur if the coke and catalyst loss can.What the byproducts.Or potential dangers and make the reactor damaged.