Can somebody explain why normal diode(1N4001 or 1N4007) is used in rectifier bridge insteed of schottky diode
Traditional diodes are cheaper than schottky diodes and they can usually block a higher voltage in the opposite direction. In most power rectification applications like yours schottky diodes are used to limit voltage drop and power loss.

In your case whether or not you need a schottky diode depends if you need to limit voltage drop or power loss.