That pump may not hold up long to acidic fumes, being cast aluminum the metal is very reactive, I am not sure what type of valves or what they are made of (possibly a stainless steel reed valves, or spring loaded ball valves as a guess, being advertised as oil less it may use a Teflon ring seal on the small piston.
Aluminum can passivate with concentrated nitric acid, so it may hold up to some nitric fumes but somehow I still wouldn’t think it would last long, the valves would have to hold up also, HCl fumes I am pretty sure it would not keep running too long.
Vacuum jar trap can help some to capture some liquids before they reach the pump, but under vacuum volatile liquid will boil at lower temperatures, even room temperature depending on the vacuum and the liquid involved.
There is not too much difference in a vacuum pump and an air compressor, or many mechanical pumps, basically a moving piston, or some other mechanism to compress air, check valves, reed valves or some other type of valves to move this air in and out of the pump, kind of like the engine in your truck, intake valves open to allow the air in as piston moves down to draw in the air on the intake stroke, as piston rises the intake valve or check valve closes, so air cannot go out the way it came in, and the exhaust valve (or check valve opens and lets air out the exhaust port.
A vacuum hose would hook to the inlet of the pump the compressed air hose hooks up to the outlet port of the pump.
To make a vacuum pump from an air compressor, you need to hook your suction hose to the air inlet of the pump, this may not be so easy depending on how the pump was made, and how the air inlet port is configured, you may have to Drill to resize an inlet hole and tap it for pipe threads, or build a small manifold for the inlet port and bolt it on with a gasket…
I cannot tell from the picture, where the air enters your pump or how the pump is made without having it here.
you may have spring loaded ball check valves inside the pipe (after where hose hooks up to the pump), I would unscrew them and check it out, and the port below (looks like it may be a valve) it may be the inlet port and may have another ball check valve, if this is so you might just be able to exchange these if the threads allow.
Have you considered using a Water operated aspirator with a trap for a source of vacuum?