php (pdo) sql, can not set limit and offset

Question

I am trying to do a query setting in the sql the limit and the offset

But all the time I get this error

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''20' OFFSET '0'' at line 8

Here is my code, any idea?

$conn = new PDO("mysql:host=".DB_HOST.";dbname=".DB_DB, DB_USER, DB_PASSWORD);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $conn->exec("set names utf8"); //BECAUSE I NEED TO WORK WITH CHINESE LANGUAGE
    $limit = 20;
    $offset = 0;
    $params = array(':limit'=>$limit,':offset'=>$offset);
    $stmt = $conn->prepare('
        SELECT
            *
        FROM
            dc_user
        WHERE
            user_status != 0
        LIMIT
            :limit
        OFFSET
            :offset
    ');
    $stmt->execute($params);