The copper nitrate hydroxy double salt readily exchanges its interlayer anions with chloride, sulfate, carboxylate and alkylsulfate anions. Alkylcarboxylate and dodecylsulfate ions are arranged in bilayers between the positively charged copper hydroxide layers. Mesopores are present in the long alkyl chain anion-exchanged HDS. In the case ofbulky anion-exchanged HDS such as caprylate- or dodecylsulfate-exchanged HDS, the process is nearly irreversible to the nitrate form, because the large difference of size between the two anions prevents a complete exchange. This limitation of exchange is not the case when the anions are ofa similar size, as for the exchange between caprylate and dodecylsulfate ion.