I'm developing a pretty basic module `catalog_request` that creates a form. I'm replacing the form's default submit button `<input ..type="submit" />` with a `<button ...>click</button>` using following in form definition.  
  
    function catalog_request_form($form, &$form_state) {

        /**
         * form fields here
         */

        $form['fieldset_submit']['the_submit_button'] = array(
           '#type' => 'markup',
           '#prefix' => '<button class="btn submit">',
           '#markup' => 'Send Request...',
           '#suffix' => '</button>',
        );

        /* ... */
    }


and have defined other two form related functions  

    function catalog_request_form_validate($form, &$form_state) {
        drupal_set_message(t('The form was validated'));
    }

    function catalog_request_form_submit($form, &$form_state) {
        die('submitted');
        //drupal_set_message(t('The form was submitted'));
    }


**The problem**  

My submit function `catalog_request_form_submit` isn't being called. I've read numerous articles online but none resolved my issue. Following didn't work  

 1. Adding `'#submit' => 'catalog_request_form_submit',` to
    `the_submit_button` key
 2. Adding `'$form['#submit'] => 'catalog_request_form_submit';` to end
    of `catalog_request_form` function
 3. Adding `'$form['#submit'][] => 'catalog_request_form_submit';` to
    end of `catalog_request_form` function

I've read that adding something along the lines of `$form['actions']['#submit'][] = 'custom_function';` could solve the problem but I'm not sure how to adapt it for my form.    
  
I know that having `'#type' => 'submit'` for the submit button makes the form work but I want a `button` tag.


My problem is exactly https://drupal.stackexchange.com/questions/64871/when-altering-the-submit-button-the-form-does-not-work but it doesn't have a _solution_ (only an answer that ignores the question's point)
  
P.S. I do not develop for drupal frequently so I might be missing something very obvious.

Any help will be greatly appreciated. thanks