The answer is; The reaction rate decreases
This is because the reaction produces more moles of gas in the products (one mole of CO and another of CL2) compared to the one mole of the reactants (COCL2). This therefore means that increasing pressure causes the reaction to shift (if it were a reversible reaction) to the left because the volume is decreases. The rate at which the molecules of the products collide is more than that of the reactants (because they are in the same container).
