The invention is directed to a surgical access system that provides access to a surgical area while maintaining pneumoperitoneum during laparoscopic surgery. , said reactor comprising a bed of granular, form-selective zeolite catalyst, and wherein a product mixture containing steam and C2- to C4-olefins is withdrawn from the bed and is passed through at least one cooling means. Each cylinder is fixed relative to one of the vehicle body and the slidable section, and each ram is fixed relative to the other of the vehicle body and the slidable section.