CO₂水合物存在于自然界中吗?如果是的话，它们能含有多少碳呢?< / p >

许多气体水合物在深海条件下是稳定的，但迄今为止甲烷水合物是主要类型，占海底天然气水合物的99%。甲烷几乎全部来自微生物产甲烷，主要是通过二氧化碳的还原过程。在一些地区，如墨西哥湾，天然气水合物也由其他热生烃气体和其他包合物气体(如硫化氢和二氧化碳)形成。这些气体从深层沉积物中逸出，沿断层上升，在海底或海底下方形成天然气水合物，但从全球范围来看，与甲烷水合物相比，这些气体的体积重要性较小。

从这里没有证据表明二氧化碳是纯二元水合物，而且重点是甲烷水合物要普遍得多。但是是的，在自然界中，二氧化碳至少在一定程度上是水化的。< / p >

One factor behind the limited occurrence of naturally occurring hydrates of carbon dioxide (and other common gases besides methane) is the solubility of the gas in liquid water. Gas hydrates exist in equilibrium with solutions of the gas in liquid water, so more soluble gases require higher concentrations to form the hydrate (which may be thought of as a precipitate). This table reveals that on a mass basis, carbon dioxide is over 70 times as soluble as methane in water under ambient conditions; even accounting for the heavier molecular weight of carbon dioxide this is still a molar ratio of over 25 to 1. For hydrogen sulfide, also specifically mentioned in Ref. [1], the corresponding molar ratio is about 80 to 1 over methane. Two-carbon hydrocarbons such as ethane can also form hydrates and their solubility is closer to that of methane (allowing hydrate formation at lower concentrations than carbon dioxide or hydrogen sulfide), but these are less abundant gases in nature.

Carbon dioxide hydrates are expected to be more widespread on Mars.

Reference

1. W. P. Dillon, in Robert A. Meyers, Encyclopedia of Physical Science and Technology, Third Edition (2001).