If you consider that liquid detergents are a product of the petrochemical industry, i.e. they started out as oil, you could hazzard a guess that a fair proportion of the ingredients are in a liquid format before the manufacturing process.
I thought powder detergents were, to one extent or another, dried from a more moist state.
Pick some key ingredients and look them up perhaps?
Do manufacturers not respond to email or a formal business letter any more? I wouldn't trust anyone on those kind of support lines to have a particularly thorough understanding of the manufacturing process to be honest. I think they're more geared up for the clueless consumer and ready to suggest another of their products as a solution to your problem. Impartial they aren't.