Copper is a very good dehydrogenating and dehydrating agent. When primary alcohol is heated in presence of copper than one h connected to oxygen and another connected to carbon leave in the form of hydrogen gas converting it into aldehyde. Further oxidation of aldehyde into carboxylic acid is not favourable. In secondary alcohol,they are converted into ketone showing same nature as above. But in tertiary alcohol,cu show dehydrating nature converting alcohol into alkene by following zaitsev rule.

Copper is a very good dehydrogenating and dehydrating agent. When a primary alcohol is heated in presence of copper than one hydrogen connected to oxygen and another connected to carbon leave in the form of hydrogen gas converting it into an aldehyde. 
Further oxidation of the aldehyde into a carboxylic acid is not favourable. 
A secondary alcohol is converted into ketone showing same nature as above.

But tertiary alcohols show the dehydrating nature converting the alcohol into an alkene according Zaitsev's rule.