I want to display thumbnails of multiple categories on a page, i am having hard time accessing the categories as it shows empty. is something wrong with my code?

                  $args = array(
                        'per_page' => '12',
                         'category_name' => 'travel',
                         'orderby' => 'title',

                    );


print_r($args); //nothing gets output, like categories
$query = new WP_Query( $args );
if( $query->have_posts()) : while( $query->have_posts() ) : $query->the_post();

    print_r($args); //nothing gets output, like categ

    //want to display the thumbnail

endwhile;;
    endif;