* Green bond issuance expected to grow in Asia (Adds final pricing and amount): HONG KONG (Reuters) - Hong Kong raised $1 billion from the sale of its first green bond on Wednesday, as the former British colony looks to establish itself as a center for green finance. Hong Kong sold a five-year U.S. dollar-denominated green bond with a coupon of 2.5%, attracting over $4 billion in orders from investors globally, the Hong Kong Monetary Authority said.