请帮我润色这段话：When CH4 is present in the gas phase the density peak of the reservoir still appears in the adsorbed state region especially in the case of pure CH4 the peak value of the adsorption layer wil

When CH4 is present in the gas phase, the density peak of the reservoir remains in the adsorbed state region. This is particularly evident in pure CH4, as the peak value of the adsorption layer experiences only a slight change. Despite the reservoir undergoing expansion upon gas phase addition, it will remain attached to the quartz surface.