> There are limits to this: containers don't handle bulk cargoes (liquids, ores, grain, lumber), large assmemblies (automobiles, wind turbine components), or high-quantity gasses (e.g., LNG). There are some rail-based options for these (specialised cars), and in other cases alternate transport modes are required.
But you CAN put liquid and pressure vessels in a intermodal framework.
The thing about bulk cargoes is that they are bulk. A total of one third of all commercial ships are bulk liquid petroleum carriers, and those ships devote all their storage capacity to one cargo: crude oil (or in some cases, refined hydrocarbons).
Similarly dry bulk carriers (ore, woodchips, fertilizer, grain), which are shipload cargoes.
Liquified natural gas is also typically shipped in dedicated vessels.
There are some instances where a smaller cargo allotment might be made, but those are almost always on very minor shipping routes.
A key concept in cargo is to use the largest and most standardised box size possible. Hence the standard 40 foot shipping container (the term TFU, or twenty-foot equivalent unit, is actually one half the size ultimately dominating the industry). In the case of bulk cargoes, a shipping container is still too small for most routes.
So: yes, what you describe exists, but it's a very minor element of total cargo movements.
But you CAN put liquid and pressure vessels in a intermodal framework.
Here are pictures of many:
https://duckduckgo.com/?q=isotank&t=ffab&atb=v407-1&iax=imag...