The present invention provides a process for decreasing or eliminating unwanted hydrocarbon and oxygenate products caused by FTS reactions in a syngas treatment unit by utilizing heat exchangers and optionally associated pipes that are substantially fabricated of a metal material selected from the group consisting of iron, nickel, cobalt, carbon steel or stainless steel and having deposited on the metal surfaces that will come in contact with the coldbox overhead gas stream an inert coating selected from the group consisting of silicon based materials, zinc based materials, tin based materials, chromium based materials, polymers, ceramics and mixtures thereof for heating up gas streams having a mixture of hydrogen and carbon monoxide and obtained from a front end purification unit/cold box unit.