dic=[{'category_name':'tv',"price":3000,"model":"1.2"},
{"category_name":"mobile", "price":8900,"model":"1.6"},
{'category_name':'tv',"price":5000, "model":"1.8"},
{'category_name':'soaps',"price":8000,"model":"1.9"}]


from pprint import pprint
data=[]
for x in dic:
    data.append({x['category_name']: x })

pprint(data)